Is it possible to solder in RB750's motherboard USB plug or RS232 plug? And connect to router via hyper terminal or putty?
Pinouts, that I have marked are correct? If you know - please explain how to do that.

You should notice, that the connectors are not the only parts missind. There is a whole lot of missing parts on the board.

May be I can buy all these parts in radio technic shop?

I think that buying, soldering the parts and testing the board will cost you more time and money than ordering a new one with all the ports already installed in the factory.

Really so difficult? Ok may be I will change my RB750 to RB450G.