@Delshon Chestnut, there are several experienced CPAs who are active participants on ths forum.

Several niches interest me, such as buy-and-hold rental properties to generate passive income or possibly wholesale acquisitions to utilize my sales background.I do not have a Texas real estate license, and want to learn some in's and out's of the industry before deciding whether or not I will need one as a future real estate investor.  

You will probably need several carriers. 

Those who are self-employed (wholesaling generally qualifies) can get the additional benefits of the Solo 401k including: Compared to an IRA, Solo 401k contributions limits are roughly ten times higher.There is no custodial requirement for the 401k.You don't need the additional expense and administration of an LLC to have checkbook control.There is a built in-Roth component whereas IRAs are either traditional or Roth, not both.A spouse can also participate in the same Solo 401k plan.The Solo 401k has additional tax benefits over an IRA when investing into real estate using leverage.The penalties for prohibited transactions are less severe, though it's best not to utilize this benefit :)

I'll be acquainting myself with Vegas more before moving forward with anything, so I'll be visiting over the next several months to understand the area better.

If you go that route you need several documents to protect you and effectuate taking over mortgage payments (POA, notice to release, etc. )If you only have a strict 90 days to do this then in your agreement that should be spelled out but several things depend on your relative and how secure he wants to be in the fact that you will basically hand the house back over to him at the end of 90 days if you haven't sold it.

I am looking at several buildable level lots for sale in the Los Angeles area, they have real streets not paper streets, they have houses most of the times on both sides... is it still a wise idea to build on a lot in L.A from scratch? 

I have several properties I hold as rentals, that have been owned long enough now that they are completely paid for. 

I had several local investors reach out and connect with me just by doing that.

It may not appreciate much now, or even take a small short term dip, but several years from now you will be set.