Holy restrictions, Batman, are you bound to some tight cuffs!
Judging from the play at Origins and my most recent experiences, if you can get someone in your group to make a serious investment in first aid (specialized in drain damage or overscasting damage as they advance and spend karma), you might as well invest in sorcery 6 and overcast your spells to close to the highest force that you can without having a realistic chance of death (1 die ~ 33-51% chance of resisting drain depending on your edge level and willingness to spend it to resist).
Making the contact rolls to acquire new talismans/foci hasn't been much of a challenge to me, 7 points from a 375 point pool might be a bit of a beefy investment, especially considering that loyalty is subject to change based on your role playing while connection isn't so much (might be if you do some awesome run for your contact, at least I'd pitch it at a home GM).
Pretty sure that you have to pay +10% between 2 characters to split a lifestyle and that a custom lifestyle from runner's companion is worth every cent. At least that's what I've been paying and if I'm wrong please, please someone correct me (I have a ton of spare nuyen and would like to correct any errors before I hit the halfway mark for prime runner, which should happen tomorrow if things go well).
With improved reaction a force 2 sustaining focus probably just isn't worth it. I'd either drop it and just take the dice pool penalty or invest in restricted gear (I assume your GM allows it) and get a force 4 sustaining focus to keep +3 initiative +3 IP sustaind unless you run into some background.
Altogether a FUN character all comes down to your personal picture of the character and your GM's willingness to work with it. A numerically sound character is another thing altogether. The guys on this forum will probably try to convince you that a power focus is a must have... I haven't had any need for one and don't plan on spending any karm or nuyen to get and bind one any time soon, if at all (but I'm playing something of a possession sock/focus addict/ backup face at the moment).