The Tesla rep told me that you have to actually take delivery of the vehicle by June 30th to qualify for the $3750 tax credit. If you order in June but don't get the car till July, it'll be half the credit. My plan (unless I want to risk loosing the credit but go for a end of quarter deal) was to order first week of June. Again, that's why my rep advised. He said a P3D or LR AWD should be 2 weeks to build.
Any new ones (Including LR RWD) all come with AEP standard, but a few of the old AEP features have moved to FSD. I think these are the auto parking and lane changing. You can go on Tesla web site and read the features for the now included AEP and what FSD adds. The Tesla rep I've been talking to said that he thought anything ordered/built in June would have the latest FSD hardware. He said that if he found me an inventory car that matched my build by then, that it would have been built in the last few months and would qualify for free install of any new hardware/software assuming I pay for the FSD upgrade.
I don't have it written down, but I think the difference between RWD and AWD was $2,000 or $3,000. You can call Tesla and ask.