Move 7:

My understanding is that the purpose of the chinese opening is that white has to invade Black's area, and during the invasion Black gets to solidify territory, or make influence.

When white approaches you play a move which means white is never going to invade the top right. Also because there is another stone at R9, you could easily play further away here than Q14.

Blacks move 7 does one thing only it makes some potential influence. White can still invade the corner later. Move 8: White plays at the top star point. White now has gained tentative control of the top, black move 7 just played in an area which already looked to be black's.

The result of this exchange is far better for white.

Move 8:

I don't like this approach, the top looks like a good place for white to develop, playing this approach gives white that chance. When Black invades white makes lots of influence facing white's stones. The result of this approach and corner invasion looks very good for white to me.

Move 18:

When white pincers I think Black should counter pincer, jumping out means white can chase blacks group making moves to surround territory, and where is Black jumping out to? There are no friends to run to on the top or left. For White to surround the one approach stone is going to take 3 moves, and the 3-3 invasion is still available, so its not really that weak, if white really wants to attack that approach stone, then Black can get some profit elsewhere.

Move 69:

The monkey jump is endgame, move 69 isn't endgame, Black needs to try and reduce white's massive top. As far as the monkey jump sequence goes Move 73 should have been at B13, this way Black would have actually made some profit. Move 73 cutting at B10 doesn't work because black's groups are too weak to be able to make use of the cut.

When White resigns I think that black is around 40 points ahead without komi, the invasion at the top of the board, really reduced white's points dramatically and black got to make a big middle. It is probably worth working out how white should have played to stop black's invasion.