1) Its normal to have 10-20 seconds of delay when everything is working correctly - if it goes above that something is probably wrong (dont know if this applies to mobile as well). Try decreasing the bitrate to whatever twitch recommends or even below that (you can find the bitrate recommendations etc here assuming youre using OBS), I found if I use higher than recommended rate it added latency. Also decreasing resolution/FPS should work too. IME client side latency usually happens because there are occasional cuts in the stream (so latency grows over time to avoid visual interruption in the stream) - check if this is the case (eg it starts at ~10s and then slowly goes up). Also see if you get dropped packets, that causes latency to slowly go up as well.

2) Streamers can 'host' other streamers on their own stream. Eg if you stop streaming, you can host another person so your viewers will now see their stream through yours, instead of just seeing that you are now offline. So this under normal circumstances is 0.

1) 1 and even 2 Minutes are normal, especially on smaller channels. Just test whether it is running without buffering and frame drops. The delay is due to Twitchs internal processing and buffering.

They added a Beta for a stream delay reduction down to 10-20 seconds, but only recommend this option when your stream is somehow very active with the chat and needs less delay. The downside is viewers with poor internet connection may have more buffering and stream lags.

2) have been already answered