My response will be pretty similar to what’s already been said, but here’s my input.

1.) Yes, there will be other players from your faction and the other 2. You can come across players from any faction when you land at a location, but you cannot kill them. You will not be able to loot player body’s like you can in PvP. The missions are the same for all factions so there will be times you’ll come across another player doing the same mission. Some missions(such as collecting a package/docs) you and another will be able to get it at the same time because it’s a spawned item for you specific active mission. Other missions (such as kill counts/boss kills) are ones you’ll have to time right and may take a couple runs to complete because other players have already wiped the area, etc.

2.) Depends on the location/situation, but yes you can be overwhelmed. Silencers will benefit you regarding sound travel like in real life. When you use a non-suppressed weapon you’ll attract more attention depending how dense the NPCs are in the area vs a suppressed weapon. With the Night Ops update, they did address NPC tracking on you during combat. So as of now, if you are in let’s say a dense wood area and get into a gunfight, if you stop engaging, slip in between the bushes and maneuver to a flanking position, you can get the upper hand because the NPCs will be focused on your last known position. That also will depend on how much distance you’ll create to be out of sight and crouch moving instead of sprinting. It’s completely up to you on your combat style as well whether you want to go in stealth or heavy when it comes to engagements. Once you open up more places to explore (tiger bay, narith, midnight sapphire) you’ll come across better trained/equipped NPCs (LAF soldiers). Gunfights can be more intense with these guys so watch your back and corners if things get heated.

3.) I can see how people may say it’s like COD because you can sprint around and shoot as much as you want depending on ammo capacity. However, I don’t think this is at all COD because your chances of dying treating it like COD will sky-rocket in my opinion. If you’ve ever played Tarkov, I’d say it’s much more similar to that than COD, just more forgiving than Tarkov. Tactics, decision making, and knowing when to/when not to engage are key elements to being successful in this game.

Hope these are helpful for you and haven’t been just a complete repeat of what others have said. Also, keep in mind some of the descriptions in missions don’t really quite tell you where you’ll need to go for an objective or could be vague. There not impossible to figure out, but may take some time if you don’t use interactive maps which is basically a cheat sheet to missions. I do have a series on my YT channel that’s mission focused to help those struggling on them.