Hey BP!

Closed on my first home 2 weeks ago and boy is it scary/exciting. It's a ~1050 sqft 3/1 SFH with an attached 800 sqft 1/1 ADU. I'll be living in the ADU while the main house is rented out. Both sides need a lot of work, though. Since the main house is rented out, I plan to rehab the ADU first. Here's what I'd like to do:

I received a quote from a contractor recommended to me from a realtor I connected with here on BP. He quoted me:

Moving bathroom walls/adding dry wall: $3K

Replacing door with window: $1K

Adding island w/ stove and oven: $4.5K

Relocating sink: $3.5K

Adding dishwasher: $600

Replacing door w/ Wall and W/D hookups: $3.5K

Adding privacy fence: $1.5K

Adding central A/C: $6K

Floors: $8K

I haven't gotten a second opinion yet from another contractor. But this contractor comes highly recommended by my realtor who has worked with many contractors on several projects. So my questions:

Are these reasonable prices? Where could I cut costs?

What work could I possibly do myself? I think I would be able to install floors(LVT) and build my own fence. I'm an engineer, I think I can figure it out! 

Install central A/C or go with ductless system? I'm leaning towards ductless since it's cheaper. The ADU currently has wall units, but they look old and unaesthetic. The homes around all seem to have central A/C. However, this property is in a really great area so I think that factor would outweigh the lack of central A/C.

Thanks in advance BP!