New Summons Menu

1) Instead of learning the spell from a monster attack, could you have an equipped esper teach the call spell like how you learn the normal spells?

It would need to replace existing magic spell then. SRAM is limited as of the numbers of spell learned at a certain percentage. Unless you do with the magic command the same thing Zeemis did with the lore command, you need to build a menu for your summon command and modify the behavior of the command. You need to code.

2) Would it be difficult to remake your patch but still keep all the existing in game commands? or is your patch dependent on Lore's function?

Pretty difficult. I once tried to start doing a summon menu but in front of the hugeness of the task I gave up. The existing patch is simply lores renamed with different attacks. It's the lore command renamed.