I've never bothered with channeling myself, I've always found it more beneficial to have casting RT rather then the little bit of extra damage that you get from channeling. The areas I hunt also tend to swarm, so being in hard RT while in offensive isn't something I'll even consider.

As you get more spells and mana you'll start using higher level spells more, but it's not really a matter of 702 being replaced by another spell so much as no longer using it exclusively. 702 tends to work best against targets that are vulnerable to crits while 705 is usually a better option for those that are difficult or impossible to crit (noncorp undead, golems, etc). For now those will likely be the main two spells you use, but as your mana pool grows, you'll start using them more and more just to do that little bit of extra damage to kill a critter rather then spending the mana for another cast of 711, 719, etc.

You are right that you'll eventually have to make more use of control spells as well as curse (if only for the hex curse), but telling you what spells to use at what level would be a mistake. It has more to do with what and where you're hunting then your level (esp once you have the mana to be making regular use of 719) since different spells are more effective against different types of critters then other spells.

Here's an abbreviated list of the important spells and their strengths:

701- good for animal type nuisance critters, having it active on a couple can possibly save your life when what you're actually hunting stuns/webs/etc you

702- staple hunting spell at low levels, works best on critters that can receive crits, good finishing spell later on

703- good for preventing anything that casts something nasty from getting a spell off, most useful at lower levels and on critters that cannot be stunned or that can cast even when missing a limb

705- staple hunting spell at low levels, works best on non-corp or otherwise uncritable critters

706- a good spell to cast on anything that can be stunned if you're going to need to be standing around it for a bit (for example, if you're going to use 710 or 718)

708- good to use against things that are immune to or can shake off stuns, removing the right hand of most magical critters will prevent them from casting

710- I used the focused version this a lot in my 20's when I had trouble beating the TD of like level critters and in my 50's on flesh golems. I still use it occasionally when my mana starts running low and I'm waiting for a pulse.

711- great for anything noncorp, esp if they have a lot of HP. Three casts of this and a shot of 705 as needed will kill most anything.

715- anything you need to reduce the TD of

718- some sorcerers swear by it, but I've yet to find a situation where it's preferable to focused 710 (maybe rooms with standing water?)

719- the more magic a critter uses, the better this spell is. Usually a one shot kill on "pure caster" critters, more likely to need a couple casts of 702 or 705 with "semi" or noncorp critters, don't bother with "square" critters.

720- When all else fails, use the focused version of this... usually doesn't leave a body to search/skin

Starchitin

A severed gnomish hand crawls in on its fingertips and makes a rude gesture before quickly decaying and rotting into dust. A gust of wind quickly scatters the dust.

On a side note, I like to use 704 first on noncorporeal critters. Seems to increase the damage done by the attack spells.