Have you already read my article on connecting to your spirit guides and higher self? I've written extensively about both. But I'll also answer these here now.
1. Guides can see what's around the bend in your river. Listening to them can help you decide if that's where you really want to row. They will never remove your free will. You're free to go over the falls if that's the experience you want to have. They'll be waiting at the bottom holding a towel.
2. Spirit guides are energetic beings with no physical form. They present physically so we can differentiate their energies better. You won't see them with your physical eyes. You'll see them with your mind's eye. They have distinct personalities. get to know them.
3. When you die you could technically be asked to become a guide but that would depend on someone's higher self asking you to "be on the team" so to speak. What are your qualifications to guide someone?
4. Guides won't help you win the lottery. that's like using cheat codes in a video game. What would you learn from that? The people who do win lotteries have lessons to learn such that winning the lottery is the best way for them to learn those lessons. If you want riches, become a vibrational match for wealth.
5. your higher self doesn't control you. Your higher self watches you with great compassion while you step in the mud, go over the falls, trip, and get gum in your hair.
6. you're assigned guides so you have someone available to point the way when you are lost. Think of them like a road map. you don't have to stop and ask for directions, but if you need to, they're there.
7. Differentiating the voices in your mind takes practice and trial and error. Read this:
How To Tell the Difference Between Your Ego, Logic, Spirit Guides and Intuition