I use Gummi pflege on my seals and it seems to keep things quiet.
Might be internally they are fogging, difficult to do anything without taking the lights apart.
The BiXenon will go in, ZMANALEX could tell you if they are a straight swap (I'm not sure on the wrinig on the plug of these) however they are pricey. Again, Alex will give you the best price in the UK if he has any. As for labour depends if they are a straight swap. If they are then two hours would do it. Or do it yourself it's very simple!
You can get the indicators with the bonnet up. I think you can maybe get the others out with the wheel turned or removed and the arch liner tanen off. Alternatively you can remove the headlight unit to change the bulbs.
I use Gliptone to clean and protect my leather. Leaves a lovely natural finiah and an amazing smell. Personally I use blackfire products to keep my car looking nice and protected. Clarkie34 recently converted to blackfire too. Others use Collinite. Basically any good wax will leave it nice if the paint is prepped below it.
Finally, bluetooth adaptor from Nissan dealer, MJP (site sponsor) or ebay.
Hope I managed to answer all the questions bud.