You pretty much answered all of the questions you asked yourself. I don't have H.I.D.'s installed but I know that you can get a dual filament bulb so you have both high beam and low beams.
If you run with the H.I.D.'s with no highbeams, your sister will run into a problem if she decided to get the car inspected in Jersey unless she has a connect with somebody or willing to pay a lil more, there are some shops that will pass it but for double the price. Another option is to yank a set from the newer Sienna's, Avalon's or any other Toyota that has them as a factory option and run them on the Solara, then you won't have to worry when it comes time for inspection. Look for a set of warranty work H.I.D.'s where a customer needs one replaced but decides to replace both and save the good one.......then you can eventually make up a set for next to nothing.
Make sure that those pieces that you swapped from the trade in Solara onto your Solara don't have VIN tags on them where it can comeback to you when they go and check the car out before selling it, unless they know about it already. I know the trunk has the VIN tag of the original car along the edge of the trunk and I'm pretty sure the front bumper has it as well. The other pieces you swapped will not have any tags......I just wanna brief you on that info so it doesn't comeback to haunt you later on.
Sweet upgrades none the less, gotta luv trade-ins........
