alright I will explain one by one:

1. SBI shares is a sponsorship through Hive account@steembasicincome. when you purchase a share for others, it means that you have one share for yourself and another share for the one you sponsor. The bigger share you have in steem basic income, the bigger percentage you will get in form of up-vote from Hive account@sbix (2,3,4,5, ...,) or if you have bought certain amount of Steem Basic Income share you will gate up vote from Hive account@steembasicincome, you will always receive an upvote from them as long as you post something (even one single alphabet). so that is lifetime upvote.
2. Yes your voting weight is determined by your steem power (sp), the higher steem power you have, the bigger voting weight you will have, and it will influence the payout of others when you give upvote. so rise up your account. the bigger payout you have the bigger sp you can earn. if you want to check you steemit activities I recommend to use this link :https://steemworld.org/@wald.sinnen. you can now anyone follow you, vote for you, or leave comment on your post, or mention you.
3. You should joint discord channel by following the link i gave you. but you may need to create your discord account, it will need a couple of minutes to have an account on it.
4. hereby, I alos encourage you to use #ccc as one of your tag when you post it but you should have this world in your post :

This is an Invitation to join #ccc for Guaranteed 👍 Daily Income 💵 and Payout 💸 for Newbies (2.0) 🐟 🐜 🐛 in #ccc 👣 and Follow 👣 the Honor Code 🏅 - the Creed (Conditions and Limits Inside) <<< please click to read.

and your post must have 200 word to meet the requirement this support is run by Hive account@freedomshift. and I am a member of this community as well, freedomshift also a supporter of PIFC

NB: Make sure to make discord channel, that channel is specifically for Pay It Forward Curation Channel, so you will meet all of us there Hive account@wald.sinnen.

hope this will help you. and if you have any question about steemit you can go to : https://steemit.com/faq.html, here is the basic rules of steemit.com. you will find the answer for most of your question.