They expect approximately 8-9% annual returns, paid out quarterly.

What they quickly discover is that virtually a single capital expenditure, a few inflated vendor invoices or a slow turn, could literally obliterate that month, quarter or year of being in the black.Likewise, PM's have to be concerned with much more than "Tenants, Toilets and Trash".

Fourth you can only take a pro-rated % of gain out tax free prorated between the years you used it as investment (non-qualified use) and the years you lived in it (qualified use).There's a lot of moving parts and you need a QI and accountant who can guide you through it. 

They are paid by the sole owner through their quarterly estimated payments and annual tax returns.From the IRS website:An individual owner of a single-member LLC that operates a trade or business is subject to the tax on net earnings from self employment in the same manner as a sole proprietorship.

Get their contact info, and call them once a quarter plus whatever other contact you choose to make with them. 

Yes mtg rates have been bumping up, and are expected to continue into the 1st quarter of next year.  

Being new to this, what are some known strategies that people use to purchase a second, third, fourth property quickly [within a couple of years] opposed to waiting for that single property to bring in enough income to afford the next purchase?

I like to use the reporting to look at metrics by year, quarter, ect

Ask to see their latest quarterly report.

I do these repairs and bill the cost to tenants following my quarterly inspections.