The re-entry permit is a permit which is added to your passport when you have an extended 1 year Thai visa. Note if you have a multiple entry Thai visa this would not be needed but a visa that has been extended in Thailand for 12 months after showing you met the financial requirements needs a re-entry permit when you leave the country.
The visa on arrival as described on this website lists the entry points into Thailand. We have now listed the countries which get a visa waiver. This means that you can enter Thailand for 30 if you arrive via the airport and 15 days if you arrive via a border crossing.
The VOA or Visa on Arrival in Thailand is available to certain nationalities. Some may only receive 15 days, others have to apply for a tourist visa before they arrive in Thailand. The VOA or Visa on Arrival normally cannot be extended as it is viewed as a temporary tourist visa. Check if your country is allowed to have a 30 day visa on arrival, 15 day visa on arrival or if your country is excluded from the visa on arrival in Thailand.
The duration of the visa is determined by the embassy which had issued the Tourist Visa. If you have a 30 visa that visa will be valid for 30 days after entering Thailand. Hence the 60 day visa would be valid for 60 days after entering Thailand. That would be the duration of the tourist visa. See the rest of the post for more information about your Thailand visa and how this gets extended in Thailand.
The non immigrant "B" or Business Visa is available to those who wish to enter Thailand for the purposes of conducting business or seeking employment. There is are a few options with regards to the Thai Business Visa. Normally the Thai embassies will only issue you with a 3 month / 90 day Business Visa as this is all that would normally be required for starting Thai Work Permit process. The "B" Visa does not give you the right to work in Thailand as this is commonly misunderstood.
The Thailand Marriage visa also called the Thai "O" visa is a visa for those who are married to a Thai national. The "O" visa is either a 3 month visa or a 12 month multiple entry visa. If you have a multiple entry visa you would need to leave and re-enter Thailand every 3 months. Much like the multiple entry Thai Business Visa it is comprised of 3 visa 'legs'. These 'legs' need to be activated every 3 months by doing a visa run.
When you decide to retire in Thailand you would need to obtain a Thailand Retirement Visa or Thai O-A visa. This will allow you to retire in Thailand and the visa would only be needed to be extended once a year in Thailand. The Thailand Retirement Visa is normally obtained in country. The procedure used by most Westerners when they retire in Thailand is to obtain a Thai Visa "O". This Thai Visa is usually called the Thai marriage visa, however it is a general visa which covers what the other don't. "O" stands for "Other" giving it a broad application.
The Thai Tourist Visa is a visa granted to a foreigner wanting to enter Thailand for the sole purpose of tourism. The Thai tourist visa can be used for 30 days or up to 60 days depending on what you had applied for. Tourist visas have become very difficult to get as Thai immigration has been clamping down on the abuse of the Tourist Visa. The Tourist Visa once granted can be extended for a further 30 days at Thai immigration for a cost of 1,900 Baht.