I just bought ChessBase last week, so I am not exactly a power user. I will say that since buying ChessBase, I've spent about 3 hours a day on it, analyzing games, looking at master games, comparing endgames, and so on. Let me see if I can answer your questions.
If you purchase ChessBase Mega 16, then you own ChessBase for life. You also get a one year subscription to updating the database itself. That means that you will permanently own both the ChessBase program, and all games that have been captured in the database from ~1400 to May 2023. If you want to subscribe to more database updates, the cost will be much smaller, as you will not need to purchase the ChessBase program all over again.
You can create your own lines, type your own thoughts for middle game plans, insert diagrams, and have an engine automatically generate lines for you. This is one of the primary things I do on ChessBase -- it's so much better than trying to use something like MS Word to annotate your own games.
Puzzles are included... kind of? I think? After I purchased ChessBase, I've been going to ChessBase.com and using the trainer in the browser version. I'm not sure if puzzles are included in the ChessBase program itself, so that's something you'll have to investigate. I think you're supposed to be able to generate puzzles from your own games, but I have not tried to do this yet -- remember, I've only been using it for a week.
Aside from master games, the things I've used ChessBase most for are: searching for similar pawn structures, searching games with the same openings, and searching for similar endgames. It's nice to play through a game, watch it fall apart, and then watch someone who is 300-500-1000 Elo higher than you play through the same game, but execute a different set of plans. The program is surprisingly good at identifying other games and sending you directly to those games.
Note that when you get the subscription with ChessBase, you also get access to weekly videos on the ChessBase website. I haven't watched a ton of them yet, but they do include analysis of hundreds of endgames by Karsten Muller, one of the most prominent endgame instructors and the recent editor of the latest edition of Dvoretsky's Endgame Manual.
There is a live pool to play, I think it's something like "Play Chess," but I personally haven't used it, so I can't vouch for the userbase, the quality of games, or anything else there.
In my opinion, ChessBase is absolutely for a serious player, and it's probably the best way to annotate your own games, figure out the mistakes in your own games, and find other games similar to your own games. I used to only annotate my OTB games because it took so long for me to do so, but with ChessBase, I've been annotating every rapid game that I've played on Chess.com, just because it's so fast. I'd say it's worth it. You won't find another program with the same functionality.
One final note: You'll probably want to set aside a few hours just poking through ChessBase and learning how it works. It's not the easiest program to pick up, took me half a day just to feel like I could navigate the program. ChessBase India has a YouTube page that has tutorials, it seems, so that's something to check out if you need more help. Note also that you'll actually have to play with the program yourself -- some of the documentation is wrong, and some of the buttons are mislabeled(!) (For example: "Tactical analysis" and "Centipawn analysis" seem to be switched on my copy, so if I want to do a centipawn analysis, I have to click "tactical analysis," and vice versa...)
If these features sound like things you will actually use often, then the price tag is well worth it, and, again, no other program competes.
looking for some peoples opinions and insights on the chessbase website.
currently my only source of study is many chessable books and puzzles on here and lichess. i was wondering about what people did prior to the creation of chessable, chessbase is expensive, so is it worth it ? say i purchased chessbase mega 16 package do i own it for ever ? or is it a subscription ? can i create my own lines and type in my own thoughts for middle game plans ? if so i think this would help remember my lines even more having to add a description of why im making certain moves.
besides following masters games in the data base what else does chessbase offer in there packages? Are there puzzles included ? and maybe my most silly question is there a live pool to play on chessbase lol? i really have no idea what the site offers other then there brief descriptions, but it is a business and they do want to sell a product to make a profit so id rather get an unbiased opinion of the users rather then reading from them. i am quite serious about chess and i do plan on entering some tournaments when they are closer to where i live, so is chessbase the next step for a serious player ?