Quick Cast Range Indicator (and an idea about Ashe)

Hello fellow summoners and possibly Rioters.
Sorry in advance for the huge wall of text, and probably bad English (not my first language).

TL;DR - I want the Quick Cast Range Indicator for some spells, such as Lay Waste and Starcall.

There is a system called "Quick Cast", as its name says, that allows us to cast spells quickly. There also is an option called "Quick Cast Range Indicator", which allows us to aim spells better if necessary. Currently many spells don't have the Range Indicator; Particularly-Coded Spells (like Karthus' Lay Waste), Point-Blank AoE Spells (Soraka's Starcall), Auto-Target Spells (Sona's Hymn of Valor), and Self Buffs which involve range or not (Garen's Judgement has range, Courage doesn't), and All-Hitting Spells (Karthus' Requiem). Haven't you seen Karthus standing too close to his lane opponent? Soraka missing Starcall? yes they're me (Hopefully) no longer!

• I wish for an option to ignore that "non-Indicator Quick Cast" setting for (most of) those spells mentioned above. especially "Particularly-Coded Spells".
• ...but "Self Buff which does not involve range" and "All-Hitting Spells" would not need the Indicator.
• I wish for an option to choose whether or not to use the Range Indicator for each spell. For example, when playing as Morgana, use Indicator for Q, W, and R (if possible), while not for E.

(Another, trivial idea; you can skip this thing below)

Ashe's Frost Shot. One of the best ways of kiting as Ashe, is hitting enemy with Q on, but not on all the arrows. The slow lasts for 2 seconds, so you would want to turn Q off to save mana, if you shoot, say, more than 1 arrow per second. Or the slow is kind of wasted.

Her Q does nothing but "slow for 2 seconds". No extra damage, but still consumes mana. More AS, more mana per second (if played carelessly). "Simply adding damage" doesn't solve the "wasted slow" problem. My suggestion is, making it cost mana over the slow's duration, instead of on shooting. This might be a massive buff to Ashe with Manamune and/or huge AS, is more complex than current Q, and requires some tricky coding around Volley, so I'm not sure Rioters would like this idea. If I could build codes, I would do like the followings.

• Costs 4 mana per second when an enemy is slowed by Basic Attack but not by Volley. No extra cost for extra slowed enemies. note: It definitely need to cost more mana, because she can slow many enemies at once, and it automatically costs mana at the very best efficiency. But cost-per-enemy would be a huge nerf to Ashe with Runaan's.
• Running out of mana (below the cost for one tick) removes Basic Attack's slow from all enemies, but does not remove Volley's. note: This should not happen so often, unless the target runs really fast as an arrow flies, or Ashe casts Volley at 62-ish mana.
• Volley's slow does not cost mana. Volley's casting mana cost is unchanged (60).
• If you apply slow from both Basic Attack and Volley on the same target at the same time, Volley's takes priority and Basic Attack's is ignored (costs no mana, but no further slow) for Volley's duration. They have separate duration and do not affect each-other's.
• Frost Shot is automatically toggled off if she has below 8 mana (as is current Frost Shot).
• Slow % and duration are unchanged (15-35%, 2 seconds).

... Then I wish I had an idea to reduce the finger-and-keyboard-destroying pain of Ryze players, ... but I have no idea. Sorry!

Thanks for reading! I would like to hear your thoughts.