Good game. You're still at the point where you can improve a lot just simply by playing, but I've tried to comprehensively address the areas you asked about.
Also, just to answer your final question, yes, both R3 and Q3 should live easily in that corner of his. I think I briefly touched on that in one of the variations, but I didn't go too indepth there, as showing too many variations for that situation probably wouldn't be helpful.
(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[6.50]TM[1800]OT[5x30 byo-yomi]
PW[kaimat]PB[Evilameba]BR[21k]DT[2010-10-17]PC[The KGS Go Server at
http://www.gokgs.com/]RE[B+Resign]
;B[po]BL[1797.665]
;W[dd]WL[1797.978]
;B[mp]BL[1794.867]
;W[qd]WL[1779.651]
;B[ep]BL[1791.655]
;W[dj]WL[1774.453]
;B[pi]BL[1788.132]
;W[dn]WL[1772.549]
;B[pc]BL[1783.656]
;W[qc]WL[1759.873]
;B[pd]BL[1781.172]
;W[pe]WL[1754.439]
;B[oe]BL[1779.244]
(;W[qe]WL[1745.63]C[Not a horrible move in itself, just slack.]
;B[of]BL[1777.392]
(;W[pf]WL[1744.594]SQ[pe][qe][pf][qf]C[This shape is called an empty triangle. Avoid it whenever you can.]
;B[pg]BL[1774.607]
;W[qg]WL[1740.697]
;B[ph]BL[1772.383]
;W[qh]WL[1738.896]
;B[qi]BL[1770.983]
(;W[ri]WL[1736.795]C[Rather small, as you are already safe in the top right.]
;B[rj]BL[1768.983]
(;W[sj]WL[1718.438]C[Overplay.]
;B[rh]BL[1766.142]C[Good.]
(;W[sh]WL[1691.21]C[Another overplay.]
;B[rg]BL[1761.819]
(;W[sg]WL[1685.505]C[Another overplay.]
;B[si]BL[1760.006]
;W[rf]WL[1674.965]
;B[sf]BL[1757.507]
(;W[qf]WL[1673.31]C[Those two stones are not worth anything, so give them up.]
;B[se]BL[1752.959]C[Now you're dead.]
;W[sd]WL[1667.315]C[Evilameba [21k?]: ^_^
]
;B[sc]BL[1746.314]
;W[rd]WL[1665.742]
;B[qb]BL[1743.543]
;W[rb]WL[1660.063]
;B[pb]BL[1741.581]
;W[rc]WL[1658.351]C[This move doesn't even threaten to save your group. This is called "Dying in gote", and it's the worst thing that you can do to yourself in Go.]
(;B[sg]BL[1734.69]C[Black wasted a move.]
;W[sb]WL[1656.208]
;B[ra]BL[1730.092]
;W[cp]WL[1643.062]
;B[jd]BL[1725.821]
;W[fc]WL[1640.837]
;B[fn]BL[1722.965]
;W[dl]WL[1631.925]
;B[df]BL[1719.977]
;W[ce]WL[1625.772]
;B[cj]BL[1718.216]
;W[ci]WL[1621.68]
;B[cl]BL[1716.495]C[Too thin.]
;W[ck]WL[1618.448]C[Good!]
;B[bk]BL[1712.149]
;W[bj]WL[1616.514]C[An excellent result for you.]
;B[do]BL[1710.342]
(;W[cn]WL[1604.001]
;B[co]BL[1706.678]
(;W[bl]WL[1601.91]
;B[bn]BL[1704.685]C[This is a failure for white - he gave up the corner completely unnecessarily.]
(;W[cm]WL[1593.608]C[Wasted move.]
;B[cq]BL[1702.688]
;W[bm]WL[1561.605]
;B[bp]BL[1684.969]
;W[an]WL[1553.274]
;B[fj]BL[1683.737]
;W[bo]WL[1547.591]
;B[ap]BL[1680.82]
(;W[ao]WL[1510.83]C[I know you know this is not the biggest move on the board. From now on, try to consider the actual value of your moves. Your group will be safe with or without this move, and it is only worth approximately one point. Don't get caught playing in an area just because that's where the action has been so far.]
;B[hc]BL[1673.038]
;W[gb]WL[1506.002]
;B[hb]BL[1670.046]
;W[ha]WL[1503.193]
;B[cf]BL[1664.633]
;W[be]WL[1499.617]
;B[fd]BL[1661.808]
;W[ec]WL[1497.852]
;B[gc]BL[1659.551]
;W[fb]WL[1496.365]
;B[ia]BL[1657.738]
;W[ga]WL[1494.711]
;B[jb]BL[1653.771]
;W[en]WL[1480.296]
;B[eo]BL[1650.905]
;W[fm]WL[1474.097]
;B[el]BL[1638.604]
;W[ek]WL[1464.094]C[Mistakes are made here by both parties, but whatever.]
;B[fl]BL[1635.688]
;W[gk]WL[1449.386]
;B[gm]BL[1632.313]
;W[em]WL[1447.319]
;B[fk]BL[1630.118]
;W[gl]WL[1446.016]
;B[gn]BL[1627.881]
;W[gj]WL[1444.352]
;B[fi]BL[1626.103]
;W[gh]WL[1423.308]
;B[gi]BL[1619.846]
;W[hi]WL[1422.078]
;B[fh]BL[1617.953]
;W[fg]WL[1419.112]
;B[hh]BL[1616.22]
;W[gg]WL[1414.894]
(;B[ii]BL[1614.656]
;W[hj]WL[1412.455]
;B[ij]BL[1611.875]
;W[eh]WL[1409.846]
(;B[hk]BL[1607.384]
;W[hl]WL[1408.176]
;B[ik]BL[1596.99]C[Oh dear.]
;W[ei]WL[1399.226]
;B[il]BL[1594.902]
(;W[ej]WL[1397.648]
;B[hm]BL[1593.218]
;W[ih]WL[1392.378]
;B[jh]BL[1590.248]
;W[hg]WL[1390.264]
;B[ig]BL[1588.903]
;W[hh]WL[1389.054]C[Again, very small. End of comments.]
;B[if]BL[1587.379]
;W[hf]WL[1387.366]
;B[he]BL[1585.612]
;W[fe]WL[1380.573]
;B[ge]BL[1583.471]
;W[ed]WL[1373.57]
;B[ff]BL[1578.39]
;W[gd]WL[1369.72]
;B[hd]BL[1574.478]
;W[fd]WL[1364.493]
;B[gf]BL[1573.248]
;W[ef]WL[1361.622]
;B[dg]BL[1568.578]
;W[qm]WL[1333.612]
;B[eg]BL[1563.886]
;W[ee]WL[1328.462]
;B[rl]BL[1561.757]
;W[ql]WL[1322.754]
;B[rk]BL[1559.744]
;W[rm]WL[1321.788]
;B[qo]BL[1555.23]
;W[sm]WL[1319.93]
;B[ro]BL[1548.407]
;W[sl]WL[1318.475]
;B[sk]BL[1546.821]
;W[om]WL[1312.644]
;B[pn]BL[1543.768]
;W[pm]WL[1310.905]
;B[pk]BL[1542.049]
;W[qk]WL[1308.639]
;B[ok]BL[1535.854]
;W[nl]WL[1304.707]
;B[nn]BL[1527.806]
;W[mn]WL[1299.962]
;B[on]BL[1525.508]
;W[mm]WL[1295.046]
;B[mk]BL[1521.926]
;W[lk]WL[1292.956]
;B[nk]BL[1517.155]
;W[ll]WL[1290.694]
;B[km]BL[1514.559]
;W[ko]WL[1286.368]
;B[kn]BL[1509.1]
;W[mo]WL[1285.036]
;B[lp]BL[1506.834]
;W[lo]WL[1283.707]
;B[kp]BL[1504.38]
;W[jo]WL[1282.61]
;B[jp]BL[1501.098]
;W[io]WL[1281.461]
;B[ip]BL[1494.983]
;W[jn]WL[1278.35]
;B[jm]BL[1493.098]
;W[no]WL[1276.738]
;B[np]BL[1487.229]
;W[kl]WL[1275.143]
;B[jl]BL[1484.845]C[kaimat [?]: gg
Evilameba [21k?]: thanks
])
(;W[hm]C[Better.]))
(;B[hl]C[Dead.]))
(;B[hj]
;W[ii]
;B[hl]C[Dead.]))
(;W[fl]TR[fj][fn]C[For instance, cut the two black groups!]))
(;W[pq]
;B[cm]
;W[bm]C[Still dead.]))
(;W[bo]C[Still the only move - you can't let black cut through your stones.]))
(;W[co]C[Your natural instinct should be to go here.]))
(;B[cp]C[You're still dead in the top right.]
(;W[ra]
;B[sb])
(;W[sb]
;B[ra])))
(;W[se]
;B[qf]
;W[qg]))
(;W[rf]
;B[qf]
;W[pb]
;B[ob]
;W[qb]
;B[nc]C[And you're safe once again.]
;W[pq]))
(;W[rg]C[Cut your losses.]
;B[si]
(;W[cp]C[You'd still be safe, and you could play away.])
(;W[pq])))
(;W[rh]))
(;W[cp])
(;W[kq])
(;W[gc])
(;W[pq]C[This invasion isn't hard to pull off; black is too high here to secure the territory beneath.]))
(;W[pg]C[This is the normal move that is better shape than yours.])
(;W[od]C[Or attack black's weakness in shape.]
;B[oc]
;W[nd]
;B[nc]
;W[md]
;B[mc]
;W[ld])
(;W[cp]C[Or just play away entirely. You're safe in the top right.]))
(;W[of]C[This is a good move sometimes. It is very severe on the opponent, as long as it doesn't leave you with too many cutting points. Here, you are fine.]
;B[pf]
;W[qe]
(;B[ne]
;W[pg]C[This is good for you, but it might be the best black can do.]
;B[nf]
;W[og])
(;B[nf]
;W[og]
(;B[ne]
;W[pg]C[Same thing as before.])
(;B[ng]
;W[pg]
;B[nh]
;W[od]
;B[ne]
;W[oc]C[As you can see, black has to make sure this doesn't happen.]))))