Laws and taxation are different all around the country but the basic premise holds true and that is as follows:  The LLC can insulate you from liability and make financial/tax planning easier and cleaner. 

The contributions do not come from your paycheck since this is individual plan, not employer sponsored plan.Yes, 401k has number of advantages over IRA, one of the major ones is exempt from UDFI taxation on leveraged real estate, I discuss benefits in details on this blog:www.biggerpockets.com/blogs/2810/blog_posts/21298-...Hope this helps, good luck!

Most states require a transfer tax at closing. 

you can elect for different taxation rules when forming the LLC.If we do form one, and we all become 1/3 owners, does that mean revenue will be split into thirds?

I learned this lesson the hard way with the 1st property where I did my financial analysis based on the tax at the time which was $5,000/yr. 

All they pay in terms of taxes given the pass through taxation of partnerships, is 15% federal + state, on the capital gains.  

It may complement your business activity quite well while not exposing your retirement funds to the taxation association with business activity.

I want to ask advice on the setup that will be best for me: 5 rentals (1 in California and the rest in Florida).  What would make the most sense?  Several LLCs in an S-corporation for asset protection?  And a combinat...

As far as taxation itself, does anything with respect to taxation change just because ownership of the property was moved to trust?

The default taxation for an LLC is pass through.