With hostages and pod crash landings, 'rescue' means they leave after you treat them, to keep them in the colony you have to capture them (in a room with bed set to allow prisoners) and convince them to stay.Nothing is stopping you from building two research benches and having two people do research at once. One of the techs you can research adds a new power-dependant research bench that's much better (and another one later adds a separate object called a multi-analyser that you need to place in proximity to the research bench to learn advanced techs). By default it's the lowest priority thing, so you might want to tell your researcher to not clean or haul (or alter the priorities in manual mode) so that they put more of an emphasis on doing it. Make sure you've got a research workstation set up and that somebody has research enabled on their job list. You can make a masterpiece of a base and it will still get destroyed because all your food spoiled in the heat and everyone is getting heatstroke in their masterfully decorated rooms because it's 500 degrees F outside.

Raiders don't generally destroy colonies, heat waves do.

Learn from what went wrong and send some more unwitting losers down to try again. Even if you do, you're still going to fail quite a bit.

Don't be afraid to save scum when you first start out to learn the mechanics.

Rimworld drop pod raid