I would recommend pale malt. Pilsner is going to be too light for an IPA, in my opinion. Plus, I find pale malt more versatile if you do decide to branch out into other styles, like reds/browns, British beers, etc.
You can do both. 2 Row is probably more typical, but a mix of 2 Row and Pils works. My last NE experiment kind of failed, but it was because I didn't use enough hops. The base I used with a mix of Pils and 2 Row was good along with the White Labs Coastal Haze yeast. If I upped the hops, I think it would have been quite good.
I use CMC 2Row, I have used CMC Pils and Rahr 2row. To be very honest, I buy 2row because it has a little more sugar and is what i have always used(it is also very cheap). Its very functional and versatile.
I have not been able to tell a difference flavor wise between beers made with pils vs 2row, used it for a while, switched back to 2 row.