Personally I am thinking 1c.

My recommendation would be to engage an investment property focused realtor (not a general residential realtor) and let that person guide you through the process from pre-qualification to market/property valuation and selection. 

Things they did bad which I wish I had asked more information about:Never involved in the screening of tenantsThey recommended keys for cash by waiving the rent amount buy only collecting fees which they would get not meThe cost to evict is 750-950 yet other companies told me they will include eviction in the priceThe tenant didnt pay in full last month and I was the one calling out to them and asking questions then a few days later I get an email saying something happened with the tenant and they are investigating.You get passed from person to person every week or so.No one told me when the construction was complete and so the house was ready for a week and the post to zillow and other sites was not done.It took them another week to take pictures and then another week to upload it.I was paying 200 dollar a month electric bills while the house was vacant because they left the AC running in the empty property.

It separates your personal assets from your business, providing a safeguard if any legal issues arise related to tenants or the property.

One thing to note when getting conventional mortgages and spouses.There is a 10 limit per person for conventional financing.You can either do 10 conventional in each person's name which would be 20 mortgages for 2 people or if you do the mortgages jointly, will only allow 10 in total.My thoughts are not to own joint assets until you are both married. 

@Enrique Toledo  If the seller is firm at 10% down, you can always get a personal loan for that 10%. 

So I wonder if I can sell my home in Idaho, purchase the new one under my personal name, then how many months or years must pass before I can setup an LLC as the owner of my primary residence, or if you think that will be a good idea? 

Real estate investment is my future.This amazing voyage begins with setting personal goals and vision.

(Either with the roofing company, a heloc, or a personal loan.)Either way you will probably be way ahead on interest saved unless you have a sub 6% interest rate.

Cosmo - I personally don't know Phoenix well, but if I had to do this in another city I would look at income levels, crime levels, and population growth (if you can) by zip code and/or area within a DMA as a starting point.