Wiring RS485/422 to RS232 converter to a given device pins
1) Yes this is correct.

2) In half duplex, rx and tx data streams both share the same pair of wires so you have rx/tx+ and rx/tx-, otherwise known simply as + and -, or B and A (or confusingly some manufacturers call them A and B).  So your wiring as shown is correct.

3) On many devices you can simply loop the rx+,tx+ terminals together and rx-,tx- terminals together for half duplex mode (RS485), but the device must support this.