Learn Italian: Il soppalco è spazioso; inoltre, mi piacciono i nuovi infissi. - The loft is spacious; moreover, I like the new window frames.

Yes, but there is a slight difference in tone. Inoltre simply adds information objectively, like "moreover" or "furthermore". Per di più and oltretutto emphasize that the new information makes the situation even better (or worse), like saying "on top of that". Since liking the windows is an additional good point, any of them work well here.

Why is there a semicolon before inoltre and a comma after it?

In well-structured Italian writing, when a connector like inoltre joins two independent clauses, it is usually preceded by a semicolon (or a period) and followed by a comma. This creates a clear pause and shows that the second point is a distinct addition to the first.

What exactly are infissi? Does it just mean "windows"?

Infissi is a broad term for architectural fixtures permanently attached to a building, mainly window frames and door frames. When Italians talk about renovating a house and replacing the infissi, they usually mean upgrading to modern, energy-efficient windows, which is what is implied here.

As a quick refresher, why do we use piacciono instead of piace here?