There is no need for the tourist visa application to have a Thai to support you. If you have to upload, just upload a copy of your own passport Id page.
Maybe maby not. There are new rules and we do not know at the moment what decisions are made by Immigration Officers. Next to that this is not the page to ask if you will get a visa or not, as described in the about section:
We can give advice, but be aware the last decision is always in the hands of Immigration Officer,
we cannot guarantee that the advice given will be 100 % successful to obtain the visa, extension of stay or entrance into Thailand.
Be aware that the new employer must meet the requirements from Immigration to make a conversion. It is easier to apply for a visa at a Thai Embassy as they have less requirements.
You never could change the reason of a Non Immigrant visa after it is issued.
You have to fly out and apply for a new Non Immigrant B visa at a Thai Embassy, be aware that a WP3 form, application for work permit is needed at most Thai Embassies to apply.
Yes, the new rule is that there is no more Extension of Stay based on unablte to travel for Non Immigrant visa holders as they can apply for the normal Extension of Stay.
And so far for the possibility to use a boat for a visa run.
It is not possible as the island Langkawi is only open for air traffic. As this page is not a travel advice page to visit other countries, I close it down.