Commercial lease investment -- need advice

[Julia Jones]

Hello BP community! I'd love your wisdom on the following opportunity: 

An acquaintance approached me to participate in a commercial lease. The idea is they'll get a 10 yr lease on a commercial space, that they'll then renovate into offices and sublease. All of my experience is in the residential market and I'd love your thoughts on how to evaluate this opportunity. 

Aside from the details (e.g. length of lease, expected revenue, expenses etc.), what other questions should I ask? What are the main risks? What is a realistic vacancy rate for such a space? What is the rate of return below which something like this doesn't make sense? I anticipate that there may be multiple investors -- anything to know there on the legal or profit-share? 

Many thanks in advance for your advice!