How are things looking at MEM? Easy to bid for after a year?
You can hold MEM almost right away. MEM and DTW are the junior bases for the 9 and ANC for the 747-200 engineer.

Does CA go senior?
Not sure on the 9, but the bus CA positions in MEM tend to go pretty senior.

Is there the possibility of higher-paying equipment there?
MEM is a DC-9 and A319/320 base only. Those are the two lowest paying A/C in the fleet- check out the payscales on APC's main website. You won't really be able to hold anything bigger than that out of training anyway so it won't matter for the first year or so. If you have aspirations to fly the 75 or something bigger, you'd need to be based in MSP, DTW, SEA (330 only, very senior), or ANC (747-200 only).