Yep you can apply for one extension each entry. No financial requirements. Because you are “changing” the reason for an extension they’ll date it from the day you apply rather than add it on to your existing stamp.
Then why fly to Malaysia at all? Unless you want to of course.
Apply for a “visit Thai family” extension and you’ll get a further 60 days. They don’t add it on to your existing stamp so do it on the last days so you don’t lose days.
No one can answer you with 100% authority to say yes or no. Entry is at the discretion of the individual officer you hand your passport to.
If you don’t have a long history of prior entries then the chances of being asked questions or even denied are pretty minimal for a second entry. You could be asked questions but probably won’t be.
Assuming you are from a visa exempt country then yes if allowed entry you would get another 60 day stamp that you could extend once for a further 30 days.
Certainly the easier option if the money part isn’t an issue. Way less paperwork and you don’t need to drag your wife down to immigration each time you extend.
You need to get your employer and you to liaise with your local immigration office to see what documents they will need. It’s generally extensive. It will be specific to your employers set up and things.