Can’t speak for others, but I’d much prefer two larger bedrooms & one smaller than three tiny ones.

How many BATHROOMS are up there? If a master bath and only one other bath? Have at it with the sledgehammer.

I agree

Depends on your skill level. How are experienced are with demo, framing, drywall, spackling, trim work, etc? If you are getting a bank loan it may be against the loan agreements. Your building dept may not allow it as you wioll more than likely need permits and a C of O. As you mention electrical work would need an electrician. Realistically if you need to ask if this would be DIY'able it probably is really not a good idea to attempt.