For switches, they're fairly simple to use. All you have to do is use the Control Switches command in an event to turn them either on or off. It'll help you to name the one you want to use so that you can keep yourself organized, so in the Control Switches menu, click the "..." button, select the ID of the switch you're going to use, and name it at the bottom of the menu.
Self Switches are even easier. Each event is allowed their own set of individual switches that only they use, so to turn one on, just click the Control Self Switch and select the letter self switch you wish to use. This simplifies things at times, so that you don't have to keep track of another switch for a simple operation.
Once you've turned a switch on, you can have it end an event by clicking New Event Page at the top of the event, and then set that event's conditions to only activate when that switch is on. If the event page is blank, then nothing will happen, or if you DO want something to happen (like with your character needing to have talked to someone else first) then you just put what you want to happen next in this new page. For the equipment thing, you'll need to learn how to use the Conditional Branches command, which essentially will do a "IF THIS SUCH IS TRUE, THEN PERFORM THE FOLLOWING ACTIONS" kinda thing.
I'm gonna assume that models are sprites (though the thought of trying to stuff a super model into a computer is kinda amusing). So, all you have to do is download the sprite into the game's characters folder, which is in turn in the games graphic folder. Or, you can download it somewhere and use your resource manager to then import that file to your game, which is sometimes what you'll have to do anyways to set the transparency of the sprite's background.
Does all of this help?