Looking at API 610 11th Edition, section 4.2.2 Pump Designations and Descriptions, your pump fits none of the models defined but is in some ways similar to a VS7 shown in Fig. 18.

If you want to avoid obtaining allowable loads from the vendor you might consider this:

Answering your questions above …. my opinion since you are not really complying with API610

1. Top nozzle is your discharge nozzle.
Side nozzle is the suction nozzle.

2. Loads on neither nozzle will have any real influence on pump performance. Therefore your closest model is a vertical in-line pump since the vectors from pump nozzle to centre-line / support are not relevant in terms of potential shaft misalignment.

3. Ref. point 2, the base plate location is not relevant to loads, but might possibly be important in a pipe stress model for expansion.