I'm super late to this thread, sorry.
Honestly where to buy depends a lot on where you're located. There are plenty of Chinese sites that have good deals and descent products. e.g. hobbyking banggood. Finding a retailer that ships products you're interested in from your continent is ideal. What to buy if you're new to the hobby really depends on you. Buy something that looks fun. This is very much a you get what you pay for type hobby. So for example a <50 dollar RC boat is likely to be less fun and durable than one that is >200.
If there is a particular type of RC vehicle that you're after and you're willing to share your region I can probably provide a more specific answer.
As for software drones without auto-leveling can be tricky. As can fixed wing aircraft via LoS. Simulators can help build muscle memory. Otherwise there is a considerable amount of relatively proprietary software used to configure various bits of hardware involved.