Tenant "Improvements"

Other

We have just done our first inspection to a property that was let by an agent. The tenants have decorated, installed a shower door (previously a curtain), new flooring in utility room and changed a number of the light fittings. While we appreciate these are all potential improvements to the property which given others experiences is great we are concerned how this affects the tenancy in various ways. I would be grateful for some advice.
1. We don't know who did the electrical work - should we get it checked by our electrician or just accept that it works and hasn't caught fire?
2. Should we just accept that they have made improvements eg the shower door and flooring and wait and see what happens when they go or should we offer to buy them at some nominal cost so they become part of the fixtures.
3. The decorating is great but far from the neutral colours we had put in what if anything should we say about it?