Vientiane will request an interview you also must go and pay in person. Just put 14 days from your application it doesn't matter really you leave when you get your visa l stayed an extra week
It's a multi entry go and come as you please for 5 years read the conditions of your visa. You should know this information it's not rocket science FFS
You are free to travel as you want. But be aware if they ask you to attend interview you will have to return and risk being asked for your passport which the embassy will see you did not stay there. Your risk it's your money so do what you like
follow this as best advise. It embassy specific. Once you know the embassy you are applying at and the category you can then search in the site. You have to do the ground work yourself if you get stuck with specific issue then ask here. Everyone is the same but you work it out yourself it's not that difficult