First of all, if you would be fit for passing PPL you would not ask a single of these questions. So, stay calm and learn. To you questions.
1. Solo only means you are sitting alone in the plane. Your FI is still responsible person and in command of you, while you command the plane. Yes, you have to have an instructor overlooking you and believe, you need'em. There is still a long road after Solo to get the license-to-learn-called-PPL.
2. Charter conditions are usually built in a way the person, club or company giving the plane does not loose money. Many times you will find conditions like rent on an hourly base with return to airfield for x£ plus a fee of y£ per day if you take the plane out. Our flight club i.e. has a rate of 250 EUR wet for C172 and 65 EUR per day with at least 2 flighthours per day billed if you take it on tour. But, it all depends on the special place you rent.
3. You should read the chapter on opening hours, airfield traffic and PPR in your text book again. Haven't you done X-country yet? If not, you are an even longer road from becoming a pilot.
4. When you are away with a rented airplane you are PIC, Pilot In Command, and close to heaven - meaning YOU are responsible. You can get away with parts of accountability by the usual insurance coverages, but if they don't pay, usually it is on you. If there is a technical issue, you are definitely not responsible for, i.e. the holder of the plane did something wrong in maintenance, you can get away, but how do you prove you not misleaned and killed the engine? Piloting means taking full personal risks, on health, life and money.
5. No, you don't. As a student pilot there is no way to take a pax - as PIC you are responsible and accountable for the life of your pax, but as a student pilot the instructor is responsible - he will be nuts to take that risk. Even if you pass exam and get a PPL you are not automatically allowed to take a pax. During the preceding 90 days to take passengers to that specific trip you have to have at least 3 T/O and Landings in that specific type you are flying - these flights have to be undertaken alone. And bet, they do ramp check you on that one!