Is there a weight limit for the table?

Yes, the weight limit of this table is about 120 lbs, SAIJI TV trays is made with sufficient materials, so it could be bear more weights than normal trays.

Is the tv tray easy to assemble? what tools are needed?

Yes, the trays is very easy to install with instruction video on product page, you don't need to buy any tools, We will give you free needed tools in the package.

Will the legs fit underneath a sofa or bed ?

The legs thickness is about 0.9 inch, so you can push legs into the gap above 1 inch,so this TV tray is fit for most sofa and bed

Is this suitable for writing or painting outside ? is it stable? I will put my hand on the table.

Yes, this table tray is very stable, you can't only use as food tray, but also use it as a writing table, painting table, a laptop desk.

Can this tray folded?

No, this TV table can't folded, because we think the most important thing of this table is stability and sturdiness, so we increased the table stability and sturdiness, but it can't fold.