I'm trying to find an online service to obtain my Texas state ID #, in order to open a bank account for my LLC, here in Texas.

You can do a ton of research online to see how the numbers pan out.

They're available online, maybe on Amazon, too. 

I have a side online business, self-employed, and my CPA suggested that I should open solo 401k with that business and move my SDIRA funds into this Solo K account since it's got better tax treatment around UBIT.I contacted IRA Services and Trust (custodian) whom I have IRA account with and they said in order to open Solo K, I have to establish my company's Solo K Plan and provide them with "Self Employed 401(k) Custody Agreement".They said I can hire a CPA or lawyer to do that.

@Katie Thompson not their job to compile a list for you, but you can probably research rcent evictions either at the court or online.

I know that on the residential side the process is pretty structured, but how does it work on the commercial step by step before you actually sign a purchase and sale agreement, that is you are expressing your interest to purchase and documenting what you need from the seller but before you make any non-retractable commitment?

Usually this is specific in the actual loan documents and that's what mine was.

That way you have a document you can enforce if the situation goes south.

Also, would you recommend seeking a lawyer to prepare contracts for wholesaling or can I just receive help from a real estate agent to prepare the needed documents? 

Start online blogging,  start creating your own business.