Is their a form when you represent only seller, and non representation of buyer.

Due to a lack of more details I'm not sure how to answer this. You represent a seller thru a listing agreement. The last page of the contract allows you to stipulate who you represent. If you are not the listing agent and you want to represent the seller than talk to your broker. You represent a buyer thru a buyers agreement whether verbal, in writing or implied. The main thing is to disclose who ever you represent and use the IBS form.

Im looking for a small home/condo/townhome with owner financing in The Woodlands. I have 30.000 down payment.

Typically owners want at least 20% down. Decent credit is good. Not too many owners can owner finance because the house must not have a loan on it that can't be paid off at closing. They also like a short payoff like 5 to 10 years. Most people can get their credit in order to refinance by then. Its a great deal for sellers because they can charge a higher intrest rate. Get with an agent and have them search for you or perhaps they have a large inventory and might know of a seller willing to do this that can't sell otherwise. GOOD LUCK!

what is the difference between pending and option pending?

During the option period which is typically 10 days the buyer can back out for any reason thus called Option Pending...Pending means they have gone thru the option period and are typically waiting on the appraisal and final approval to close. There is also PS which means Pending continue to show. Typically this is used when a seller desires to still show the home for back up offers in case the first one falls through.