Singaporean looking for answers regarding visa and work permit

Hi everyone, I'm a Singaporean who is confused about the procedures about getting a long-term visa and work permit in Thailand. Siam Legal does not provide the services for citizens of Singapore. What I would like to know is:
(1) the steps taken to apply,
(2) the documents needed,
(3) the conditions of a visa and work permit, and
(4) whether I have to travel out of Thailand every 90 days. (Is there anyone who stays in Thailand more a year without leaving the country?)
I'd be really grateful if any Singaporeans can share with me their own personal experiences about what to do, tips and recommendations, and so on. Thank you!

You will find all informations on the website of Thai Embassy in Singapour for Visa B : http://www.thaiembassy.sg/visa-matters- … ant-visa-b

Regarding your questions about 90 days, you need to report to immigration every 90 days if you have a single entry visa, if you have a multi entries visa you can go out and in the country but can't stay more than 90 days each time