I have a few questions about sovereign planets if anyone knows the answers…
Does planet size or tier affect gleam ball size?
What is the biome that has the hills made of wood (and can you get it on any tier).
Same as above for the large blocks of gleam that are not ball(s).
How do I check if I unlocked any new colours?
10char
Tier doesn’t affect the size of gleam ballz. What will make bigger gleam locations is when some biomes mix together and you get lucky. Usually will happen on higher tier planet (it’s where I have been luckiest with it anyway)
Biome with wood hills is on T4 + planets. It’s a tier 6 or 7 biome iirc. Called Island Trees
Want a low tier world where I can build a few farms and cycle through colours, think its going to take quite a few rolls to get the right gleamball though… They have all either been to small or not in the right spot so far.
No, but what can affect them is merging with nearby biomes, and if the Gleam Lake biome ends up really small in an area (which can happen either from having a ton of biomes or Gleam Lake in an area with tons of mountains). The large blocks of gleam that aren’t Gleam Lake usually are the result of it merging with another biome. Gleam Rain can do this too, but doesn’t seem as common. This can be good or bad, sometimes you get too much other material mixed in or a thin layer. If you aren’t wanting to experiment, main thing here is just knowing that a lot of the floating terrain biomes can do this (floating shrapnel, sky pattern are a couple) though usually you’ll still have some regular spheres.
Sounds like the stumps of Island Trees. Can get stumps or hills of wood from this biome, especially from merges. One of my favorite biomes - the wood underground is pretty solid (on the surface the trunks are hollow and rock), and the canopies of the trees are great bean and glow cap farming. 
Level 6 pick, IIRC, so need a 4 to get it.
I have had some luck generating bigger gleamballs on lower tier planets by merging the big sponge mound biome with gleamballs. An additional benefit being that often the gleamball is at ground level. It’s all luck though.
Thanks for the answers. Managed to roll a nice little T1 with some ball(s) in the right position and some good redwood clumps for me to set farms up on. Going to try keep it fuelled long enough to work through all the unlocked gleam colours, and will try setup a few farms for different resources and take requests for colour changes. Will make a thread once I have built some farms.