You would need to terminate employment or still be working with the employer beyond age 59 1/2.It is also not possible to use IRA/401k funds to supplement a personal investment. 

Most just do a few sales the first years and then go out of the business or pick up another job to supplement their income.

DO NOT use some generic template from online without making sure it is appropriate for whatever it is you plan to do.

Once you're established, have multiple properties, or it's a business, then I suggest as others and request a document review and an hour or two from an experienced real estate attorney.You probably need something in place, but please don't try creating your own or download a generic non-MN one from a blog.

I do a lot of communication via email with prospective and current tenants, is the best way to just get a generic email for each LLC or share one or is that an issue to have separate emails? 

I am still interested in buy and hold and developing passive income to supplement and diversify my traditional investments, but am getting the impression that the market may be too tight to even start. 

Not raising a tenant to market rent, regardless of what that is, means you are supplementing your tenants rent out of pocket. 

Your question is pretty generic.

I see real estate as an opportunity to supplement my income and be more self sustainable.

It usually takes the county about 6 months to catch up and "work" the transfer so buyers typically receive a supplemental bill 6 months to a year after their purchase for the portion that was "missed" in the prior tax year.