A couple of things: forgive any gramatical or formating issues as I'm on mobile.
For the value of your car: You need to look at NADA dealer value for the car not KBB. Most insurance companies use NADA, and they use the retail (not private sale) values. For value purposes unfortunately just being an owner of a car does lower the value. The saying that a new car loses 30% of it's value the moment you drive off the lot is very true. The insurance company doesn't care about your attachment or your plans to sell it unfortunately.
Beyond that point it does sound like you need to get your adjuster on the phone and talk to them. The tone I'm interpreting from your interactions on this post come off as kind of hostile.
I say that because in an earlier post you mentioned that you communicated everything you were doing to the adjuster, but unfortunately that's not how it works in insurance. If your just telling someone what you plan to do without asking what your policy covers or what the company's policy states about something...Your going to be disappointed. If you talk to them and gain an understanding as to why they are doing certain things they are much more inclined to work with you. Adjusters want to help people , and it's not our money (we don't get bonuses for keeping payments low or that other bullshit people think), so most will help you if you have a valid concern and appropriate documentation. Most insurance companies care way more about the customer service versus saving a few a grand on one claims, and that message is especially true for an auto policy. For instance when i was an auto adjuster, if someone was deadset on wanting something replaced vs repaired I would be more than happy to work with them and the body shop, and most time give them the benefit of the doubt. However, I still needed to follow my companies protocols, and I'm certainly not going to want to go out of my way to help someone who comes off as pushy or unreasonable.
Most insurance contracts (which you signed when you got insurance) give the insurance company control regarding what to pay for damages and how to initially approach the repair. Obviously going to go with the coat effective method (Iike repairing instead of replacing certain parts), however they all have a process for your body shop to submit supplement requests with documentation. I can't tell you the number of times I had people complaining about what a body shop guy said needed to happen, but then when the shop called us their reasoning was nonsense and really just a way for them to get some extra money.
Regarding Parts being re placed ...Replacing parts can and absolutely does affect the value simply because some people are turned off by the idea of driving something with replaced parts whether they are OEM or not.
Regarding the rental, again the limits are set by your insurance contact. $900 is the max you purchased but rental companies do have cars that are $30 per day, out the door, including tax. Keep in mind that while insurance companies partner with rental companies for customer convenience they are totally separate companies and your insurance adjuster has zero control over what the rental agent sold you on or what the rental company charges. Most rental companies have cars for 19-25 bucks a day, which is under the 30 a day limit after taxes. You just have to make sure your specifically ask for that...Otherwise they (the rental companies) will try to get every dime possible from you above the $900 they are guaranteed by insurance. If you sign any agreement or initial anything with the rental company, make sure you are looking at the total price of the rental, as it is easy to miss where an upcharge may have been left ok the agreement or someone made an error. When you come back that rental rep isn't going to remember you, so all they have to go off of is the contact you initial and sign.
I hope that helps a bit.
Source: Enterprise employee for 2 years, current adjuster previously in auto and total loss/theft for a total of 5 at a major carrier.