no you can leave and do this alone. You just need to have the correct original documents with you. Sometimes you'll need a letter of invitation from the mother/wife. Thai embassy Savannakhet have list of everything you will need and the last time I checked it was all correct. They even answer the phone ha ha.
Scroll down the page and you will see a story from someone who got denied boarding exactly like this. Immigration supposedly share info with airlines and they will deny you boarding if your name comes up.
It needs to be transferred into your account from abroad and be in there for two or three months. Can't remember how long this second. But you don't need this for the first 90 day single entry. You can go and get a single entry from Savannakhet easily and apply for the year visa when you are back in the country. I'd recommend Savannakhet as they are fairly relaxed about everything there and you don't need an appointment. Fly from Don Muang to Nakhon Phanom and then get a minivan to Mukdahan border crossing. Then across the bridge to Laos. Very easy process.
I've done the whole process for as little as 7-8k before. But if you want to fly and enjoy yourself a bit when your there about 15-20k. 15 is well doable if you watch your cash.
for the non immigrant 90 day single entry it should be fairly easy to do it all yourself for about 20k. It'll be way better than a tourist visa or visa exempt.