Rs485 to UART convension
1) Those RS485 drivers are bidirectional. They have a transmit and a receive circuit inside. That is why you see the two pins DI (driver input) and RO (receive output).



2) It depends on the data rate and/or the distance between the nodes. That is, for long runs of cable, you may need it, same it's true for high data rates. So I would put those there just in case, anyways, you can always make it flexible and add those termination resistors via jumpers so you can enable or disable them as needed. This is intended to match the approximate impedance of the commonly used cable for RS485 (anywhere from 100 to 120 Ohms).

3) You don't have to short them. But the RE (receive enable) is active low and the DE (Transmit enable) active high. So by tying them up you can either transmit at one time (by driving them high) or receive (driving them low) half duplex. You can drive them independently (without shorting them out) if you have the need to receive and transmit at the same time (full duplex).

4) from my experience, those RS485 drivers are very generic since they have been around for a long time. In fact, you can find them with the same pinouts (and package) so that if you need to replace them, you just drop another one in. But double check it.

5) Just a bypass capacitor between VDD and gnd close to the RS485 driver is what you need.

Hope it helps.