Let's see.
COMBAT
From recent experience, I've found a good way to speed up combats is full disclosure. When a fight breaks out, post all the important details about the enemies, so that players know ahead of time what numbers they're aiming at. That way they know whether or not their actions succeed, and can describe their posts accordingly.
Encourage players to take the list of combatants, and update it in their posts to reflect what they did. That way the next player has a current situation to go by, rather than trying to guess.
It also helps to worry less about initiative. The simplest model is to just let all the PCs go first, in whatever order they post, then have the enemies take their actions. If the order of actions is important, you'll need to make sure your players can check in often so that they don't miss their turns. (Just in case, though, you'll want to establish a rule akin to "if we go X days without you posting on your turn, the GM will take your turn for you".)
PLANNING
Any game can fall into the trap of over-planning, but Shadowrun-style games are especially prone to it. It's hard to avoid, partly because the whole round-robin of gathering information, making plans, and acquiring gadgets is part of the game.
Here's a trick I came up with that might help. It takes a cue from heist films like
Ocean's Eleven.
When the group is planning a job, let them have some time to work out things ahead of time. Maps, tools, knowledge, that sort. Set a limit to how long they can work at this, then ask them to 'set aside' specific amounts of time and money. The first few times you use this method, be flexible on both. Once they've decided on how much to 'use', start the job.
During the job, things will inevitably come up that they didn't already plan for. A security guard in an unexpected place, or a locked door, or a computer that needs to be used, or a room full of VIPs. Whatever. When this happens, switch to a flashback of the planning phase, and let the players work out how they might have learned about the obstacle in advance, and what they would do about it.
Figure out how much time and/or money would have been used in getting around the obstacle. Deduct these from their 'pool' of time or money, then switch back to the action -- except this time, retroactively apply their plan. Maybe they stole or duplicated a keycard to get past a locked door. Maybe they learned the guard's patrol route. Maybe they made a disguise. Assume they took along whatever they need, get past the obstacle, and move on.
Keep switching between the planning scene, and the action, as needed. If either resource runs out, it'll draw more on the other. If they run out of planning time, then anything else they need will cost more money ('cause they're in a rush). If they run out of money, anything they want will take extra time ('cause they're having to bargain). And if both run out, they're on their own.
PC BUILDS
Really, this one's up to you and what sort of game you want to run. How well-equipped do you want them? How well-informed? What part of what's really going on will be initially hidden from them?
Street Scum will be poorly-equipped and outnumbered, but have a realistic viewpoint on events. After all, they're living in it. They might be ecoterrorists or anti-establishment, but in any case the odds are against them and they'll have to be very clever and resourceful to succeed.
Shadow Operatives will be better equipped, but only get the bare minimum of information from their employers, and often that info will be selectively edited. But then, they'll
expect to be lied to from all sides; rooting out the truth and acting on it is part of the business.
Corporate Operatives will likely be very well-equipped and get curated missions with pre-op briefings, but they'll be going into missions with their knowledge biased toward the company. The actual impact of their goals may not be immediately obvious, and discovery of such may lead to them going rogue.
Military Troops will be the best-equipped, even given experimental tech, but may be about as well-informed as shadow ops. In their case, however, they're full expected to simply follow orders without question, and to not dig for the truth.
GENRE
Simply put, you're not really running a Shadowrun variant any more. It sounds more like Ghost in the Shell with a bit of wuxia and horror thrown in. When you set up the game, just describe the overview the way you did in the first post, and that'll make it clear what you're doing with it.
In any case, I recommend making a handful of pre-generated characters. This will give examples of what sort of characters you're expecting, and you'll have the option of simply handing them over to players so they can get started quickly.