Set up LLC in Texas

I just got the paperwork from my new company. The member is a company from Spain, so I guess the paperwork needs to be filled (as register that company in Texas). The company provides consulting services (i.e. software integrations). Clients might be from Spain, so I need to know how to invoice these services and what forms do I have to fill in regarding the foreign clients. Questions I need to be answered are: 1) What forms do I need to fill and when? 2) What information do I have to write when making invoices? 3) If the LLC invoices to other companies (alien companies) for a trademark fee, how to invoice it and tax it? 4) Can I buy a house thru the LLC? What taxes do I pay for renting it? 5) What is the tax rate? If I am the sole manager of the company, do I have to get a salary? 6) What applications do I need to fill up? Application For Sales Tax Permit And/Or Use Tax Permit - [Form AP-201] Online Tax Registration Signature Form (Form AP-215) Resale Certificate Form [01-339] Tax Publication: Taxable Services AP-220, Instructions for Completing Texas Sales and Use Tax Permit Application