I\'ll take these one at a time...
- There are two types of transports in the game. Dedicated Transports are bought as upgrades for a squad, and this squad that bought it is the only unit allowed to start the game embarked in it.
- Other vehicles have transport capacities, but are NOT upgrades - these vehicles may start the game with any unit embarked on they that the owning player wishes, as long as there is space and no other special rules prohibiting this.
So then...
- You may buy a razorback as a dedicated transport for any unit that says you can in the unit entry (the entry with all the points values).
- The whole squad does not need to fit into their dedicated transport. Some people like taking Razorbacks as cheap, armed, moving pieces of cover for 10-man squads. Its a good strategy - and if you take casualties, it gives you a way to get out or redeploy.
- A Master of the Forge does not have any option to take a Razorback or any other dedicated transport, at least not that I could find. Neither does a unit of servitors. You could mount these guys in a Land Raider, though.
- A Valkyrie is a Fast Attack choice that has a transport capacity. Since it is not a dedicated transport, any unit (within the restrictions listed with the Valkyrie\'s description) may start the game embarked in it. Storm Troopers are good choices for this.
- The shortest time between new editions of codexes that I could find in the last twelve years was the three years between the 4th edition and 5th edition space marine codex. It was 6 years between the 3rd edition and 4th edition rules, and 4 years between the 4th and 5th editions.
If it takes you 3 years (or more) to figure out Warhammer, I\'d say that\'s not a problem with the game.