How can I do this please if I have 2 separate clients?
1. I have an ongoing client - I already have the Tracker for that.
2. How will I set up the new client I just got and Track the work accordingly?
On payment of new Client
1. Will Upwork take off 20% again until $1k or can it be less? (I've already met the $1k quota on Client 1)
Active hourly contracts should be available in your Upwork Time Tracker. You just need to select the correct contract that you will be tracking the hours for so that they get uploaded to that contract's Work Diary. You don't need to download the Time Tracker again to track the hours for the new contract.
As for the sliding fees, they are the same whether the contracts are hourly, fixed-price, or projects on Project Catalog.
Kindly check out this help article for more information about the freelancer Sliding Fees.