Truth is there's no right or wrong answer in terms of what TF to use as it's highly dependant on your strategy/style. The TF to use would also be dependant on what stocks you are trading. For example: if you only trade highly volatile and fast moving stocks only when high volume arrives, most traders would only trade the 1/2/5 min TF and feel the other TF serves no distinct purpose as they would often be in an out within seconds or minutes usually.
You likely notice by now that my style is often more geared towards holding a stock more than seconds.. (though I must admit I do pick up one of those FOMO type actions from time to time if it's at the right timing and risk controls in place) and moreso upto a couple of hours if I DT.. so I'd usually trade from a 5/10min TF and use a larger TF such as the 1 hour as a reality check to support my assertions.
Taking into account the above, see below for responses to your questions:
A) The larger TF (e.g 1hour) helps paints a bigger picture of what is happening as the day progresses but IMO it's important you still rely on the smaller TF for both your signals and confirmations.
Firstly it becomes extremely confusing and distracting if you are using 1 TF for a signal and another for confirmation. Secondly, the larger TF such as the 1 hour is delayed when it comes to quick sudden movements/action and by the time you got confirmation you might have missed an entry or lost a few pips. Again, you'll need to find that balance as there's no right or wrong answer here so you'll need to find your balance or choose to operate on one TF. I notice the ones who have been here awhile are able to be flexible across multiple TF and adapt the relevant TF to the pace of the stock they are trading as well. That's a skill you'll pick overtimr as gain more experience so just keep it simple for now.
B) Capturing action from previous trading days is precisely why using a larger TF to support your assertions on a smaller TF can be advantageous. May help pickup Accumulation/absorbtion/distribution ideas and help find entry and exits based on support/resistence established from the larger TF candles. If I'm DTing I'd only take a quick glance at the daily at the very start to establish key pivots but rather use the 30min/1 hour to form ideas and vaguely support decisions though.
Hope the above makes sense.. Let me know if anything doesnt. Cheers.