Can I list projects I worked on while employed in my brochure?

You can put your past jobs on your resume and brochure, but you have to be careful not to misrepresent who owns what. Your former architectural firm or their clients own the copyrights to the projects' plans, and renderings, and models, and the hotels and other clients own their trademarks, so any use of the copyrighted works has be to be "fair" and any use of the trademarks has to be "nominative."

1) Yes, if you take the photo, you won the copyright to the photo. You should represent that the project twas done while you were employed at your former firm.
2) This rendering was done by you while employed at your former firm and beloings to them. You should request their permission to use it and indicate how you will attribute credit for the project to them. Maybe they'll agree to reciprocal hyperlinks to each others' websites.
3) Same as #2.
4) Yes, again with attribution of the projects to your former employer
5) Yes, if you identify that any trademarks used as owned by the rightsholder.

You may wish to consult an IP/business lawyer to make sure your new business is structured properly and its IP assets are handled correctly.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.

Thank you very much for your answer!

Do I need to seek permission from the building owner to place the photo of their building on the brochure?
What do you mean "nominative"? Can I say I worked on a Hilton hotel?

No, you don't need the permission of the building owner to show a photo of it. There's a right in the Copyright Act specifically allowing photos of a building in a public place. Your photo can include the trademarked name in it, you just have to give credit of ownership of that mark.

"Nominative" for trademarks is like "fair use" for copyrights. It's the limited right to describe something, even while using someone's trademark. It's not infringement because you're using someone else's trademark to describe the building and your work on it, and the only way to refer to the projects is to use the client's trademarked name, e.g. Hilton.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.

Thank you!

As usual, Ms. Koslyn's information is spot on. I write only to reinforce her admonition not to leave the impression via your "company brochure" that you were responsible for creating the designs for the buildings that were created when you worked for your former employer.

There's a whole body of law -- separate and apart from intellectual property law -- that controls what you can and can't claim in advertising. Advertising law is a niche specialty with rules unfamiliar to most attorneys -- and many intellectual property attorneys. I strongly suggest that before you distribute your brochure that you have an advertising attorney look it over. Because you're now a competitor of your former employer, that company will most certainly look it over carefully -- and may complain about "false advertising" if anything is amiss. Good luck.

One other thing: Licensed professionals (attorneys, doctors, accountants, architects, etc.) all must abide by the state licensing rules applicable to their professions - and those rules sometimes incorporate the ethical standards established by the profession's main industry organization (the American Bar Association, for example). You should, therefore, look up the advertising rules established by your state's regulatory body that controls the conduct of architects.