New CBB

I'm creating a conworld, and I want it to be scientifically accurate, so I'm going to include tectonic plate boundaries and movements of the plates in my creation. However, I'm also going to create a conworld with very little land, or at least less amount of it than in case of our Earth. I know, that having huge amounts of water is probably a condition for having plate tectonics for planets with size of Earth, and worlds without oceans could have plates only if they were bigger. However, I don't know, how would a plate tectonics look on a planet that I'd like to create: would it be significantly differenet with respect to sizes of plates, their movements, distribution, etc? Or maybe plate tectonics would be impossible?

How about other features of such a planet: would it be possible to keep little area of land surface without risking it's erosion and dissapearance in relatively short time (perhaps shorter, than one required for evolution of land life)? And for average ocean depth: would it be greater, or smaller? I think, that for keeping small aea of land it would be required to have deeper oceans, so as water could cover more area of continents... however, that probably could cause quicker errosion of remaining land... or am I wrong?

Thank you in advance, for all answers!

I don't know the answers to many of these question, but I will point out that the land areas would have to be very, very small to fear rapid erosion of the kind you're implying, so I think you'll be safe there. Also note that tectonic activity means some plates will crash into eachother at some point, creating new land when they buckle and form mountains. You'd also have volcanoes.
I would speculate that for an Earth sized planet, you would indeed need deeper oceans but I also suspect that this will do little to affect the plates' movements.

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I speak English and a touch of Gàidhlig.
I am creating a conworld, which I refer to as the Carrion Series, that will contain three languages, Iriex, Dvoen and Maxna.

Over time, lighter rock tends to accumulate higher up than heavier rock. For example, basalt, common on the ocean floor, is denser than granite, common in terrestrial mountains. Continental plates are basically regions where lighter rock has puddled on the surface. In some cases these puddles break the surface (i.e. continents and islands), in some cases it doesn't (i.e. sea mounts and underwater plateaus). There is a limit to how high these puddles of lighter rock can go. So if you introduce more light rock to your world, the continents are probably going to get wider rather than taller. And if you subtract light rock, the continents will probably get smaller rather than lower. For the most part. So, if we assume that your planet is the same size, has the same amount of water, and has the same level of techtonic activity, we can probably make believably large oceans by increasing the overall density of the planet. Then again, maybe it's easier to adjust some other variable, like techtonic activity, or the amount of water present. Erosion isn't an issue, since continents replenish themselves through plate collision. Ocean salinity is also not an issue, like some sci-fi writiers have erroneously believed. There's no reason why smaller continents would prevent techtonic activity similar to Earth, but the plate boundaries on Earth do seem to act slightly differently in the ocean and on land, so keep that in mind. The depth of the ocean is entirely up to you. If you take an Earth-like planet and simply add more water, you'll get deeper oceans. If you keep the same amount of water and make the continents smaller, you'll actually get shallower oceans, since the water level will drop slightly. But it's your planet and you can dictate precisely the amount of water you want, so there's no need to be concerned about that. So far I think your idea is fine. Let us know about new developments.

I’m not a scientist, but I do have access to Google and some thoughts of my own. Are you absolutely tied to needing plate tectonics? From what some science pages told me, it seems entirely possible that a planet could exist made out of 100% Liquid. Past a certain depths it would turn to ice. This would also get around the problem of mountains. If you did have plates made out of ice, and they jutted up by crashing into each other, the exposed land-ice-mass would eventually melt back into the ocean, keeping the process near eternal.

Of course if you are trying to be scientific, now that there is only a liquid planet base you have to wonder, where did the elements come from to make up the life forms? On earth life is carbon based. If this planet coalesced from a cloud of liquid elements they would be have to be formed from the same elements.