bass traps..which wall first

The first corner reflections would be from the corner closest to the speakers, obviously enough. So the front corners should be treated first.

Using different size traps allows you to trap different frequencies so that's not a bad idea. It would be good to determine what your problem frequencies are likely to be first, then choose a trap size for that frequency.

what are your thoughts on accoustical solutions traps up front (the 4' tall foam ones) and Aurelen Lenrd bass traps in rear (2' tall)

Auralex Lenrd traps in the front and rear corners, each 2 foot tall stacked in threes to create 6 foot stacks in the corners, works very well for me. A rug and some furniture and I'm done. I wouldn't want to lose some of the remaining ambience in the room.

I have some rock wool (8lb) four inches thick on the diagonal of the corners behind the speakers. I could not believe the difference it made. I highly reccomend it, especially if you have squarish room dimensions. I haven't personally tried all four corners, but if I could I would definitely do that as well. The other thing to think about is the first reflection from the ceiling. If you have speakers with good dispersion in the tweeter, you should put some damping in high frequencies on the ceiling, in my opinion. Ambience is good, first reflections are bad, again in my opinion.

what are your thoughts on accoustical solutions traps up front (the 4' tall foam ones) and Aurelen Lenrd bass traps in rear (2' tall)

I'd be inclinded to go for the MEGA LENRD's (or equivalent size) if you plan only a total of 12 linear feet of coverage in the corners (4' + 4' + 2' + 2')