If you quality you will enjoy the benefits such as large contribution limits up to $61,000 per year, exempt from UBIT tax on leveraged real estate, ability to invest tax-free using Roth sub-account and more.

Are there exemptions to which you don't qualify for as an investor that make the property tax nearly double?

It looks like loan secured by a real property is exempted by CA usury law.

But once we move into the residence and no longer rent it out, won't we no longer be eligible for the capital gains exemption?

If so you could do a HELOC, Cash out refi, or sell and be exempt from capital gains (as long as it was your primary 2 of the last 5 years)If not, a HELOC will be difficult, most are for primary residences only. 

Generally rental real estate is exempt from UBTI under Sec 512.An IRA does not avoid UBTI via UDFI if the rental real estate asset is leveraged (per Sec 514).Generally, an IRA would not have UBTI exposure on unleveraged rental real estate, however it is always best to have the conversation with your tax professional as this area of the tax code is not simple -- even a lot of professionals mess it up.

Example: rented for one year, resided in for 2 years, 1/3 of gain is not exempt; lived in it for 3 years, rented for 1 year, 1/4 of gain is not exempt.This is because you rented it Prior to meeting the 2 years as your residence.

There are a lot of DAV exemptions on record now. 

This should be simple to look up with the county they will list all applicable taxes and all applicable exemptions along with their amounts. 

One tip is closely track your interactions with any potential investor, but in any circumstance when you enter into the syndication/private investor arena you need to be familiar with the rules so that you do not blow an exemption or break the law.