eComfort will even give you the names of qualified contractors in your area if you need it - at least they did back in 2014
I found a contractor by just going to their website and then I touched basis with them before I placed my order with eComfort
http://www.mitsubishicomfort.com/contractors
When it came time to have it started up - the original contractor backed out saying he was getting pressure from the Mitsu Rep. (I think Mitsu was starting to try to crack down on internet sales about then) I went to my #2 choice and they treated it just like a service call. Flat $300.
The Mitsubishi's should not need any additional refrigerant, they come precharged up to a set length. On mine, for example, there was a sticker on the side that said it was pre charged up to 131' of line - between the two indoor units I had maybe 65'
I sent him a bunch of pics via email so they could see exactly what they were dealing with without having to come out to the house
I still have the contract proposal:
For you review, we outlined the scope of work as follows:
• Perform start up on Mitsubishi mini-split system w/ two indoor units
• Nitrogen test refrigerant lines and bubble check all connections for leaks
• Pull vacuum on system.
• Start up system and check. For proper running pressures.
I would definitely do it again with eComfort and Mitsubishi. I am not that concerned about the warranty - that I why I bought a Mr Slim to begin with
Edited to add - if you go Mitsubishi, you need to register your system on their website
https://www.registermehvac.com/claims_1.aspx?promotion_id=7606
Also Warranty Info
http://www.mitsubishicomfort.com/tools/warranty-registration