What happens at the end of the contract?
Removal, the remaining stock and the state of the wall behind it. All three should be in writing before installation, not after.
The least exciting question in any proposal and one of the most revealing, because it is the one providers have most often not thought about.
Removal
Who takes it out, at whose cost, and within what window. Under a provider-owned model this is unambiguously theirs. Under a building-owned model you own an installation you may no longer want, which is a materially different position and worth pricing at the start.
The stock
Whoever owns the inventory owns whatever is left in it. Say so explicitly, because a stock of part-used consumables and second-hand equipment has a value somebody will eventually argue about.
The wall
Making good. Fixings, cabling, power, and the finish behind where it stood. This is a small cost that turns into a dispute precisely because nobody wrote it down.
The residents
The part that gets forgotten. People will have organised a year of their habits around the thing. Who tells them, how far in advance, and what happens to outstanding rentals and account balances.
Get this answered for your building
A proposal states which figures are contractual and which are estimates, in writing.