1) Sounds reasonable. Pure PD ships may be worth considering, probably based on railguns (Gauss requires significant research effort to become competitive). Lasers are fine dual-purpose weapons, but for pure point defence they don't really compete even when turreted.
2) General purpose ships or specialisation is a personal preference. Sometimes you have a choice between an integrated solution or tacking on something else - e.g. if an offensive laser ship needs some point defence capability, you can either turret the weapons or throw on a few railguns. Preferred approach may depend on details (slow ship = turrets, fast ship = railguns?).
The problem with a balanced approach is that overwhelming force in one aspect lets you skimp on other aspects without losing effectiveness. If you completely outrange enemy missile threats, you don't need defence. If your beam point defence makes you invulnerable to enemy missile attacks, you don't need missile range. However, a balanced approach is often more fun to play.
3) Depends. The defaults are subtly discouraged by Aurora.
1.0 power engines are ugly because of how costs scale (1.2 power is 1.2 times as expensive, 0.8 power is 0.64 times as expensive).
Having your speed match your base BFC tracking speed is also ugly. Faster gives you better tracking speed without turrets, slower doesn't lower it.
A fast beam ship that outruns and outranges the enemy can take down an unlimited number of beam ships - very fast works here.
If you can defend against any missile threat and blow up the enemy before they enter beam range, you don't need speed. The same applies when the enemy never even sees you (stealth, very long-ranged missiles, tiny missile fighters). Very slow works in these cases.
If you rely on railguns or other non-turreted beam weapons, going slightly above "standard" speed gives you correspondingly more effective firepower, meaning you get the additional speed almost for free. Moderate speed works here.
4) For point defence, usually not, especially not if you have few weapons per FC (small ships, or as a precaution against many small salvos). Take into account that the first shot will have very poor accuracy, if there's a chance you won't get the second shot off at a good, i.e. low, range it may be preferable to keep the weapon in final fire mode.
While many approaches work, I think it makes more sense to start with dedicated long-range beams and dedicated point defence. Integrated solutions are easy to mess up (paying through the nose for something that doesn't perform accordingly) and requires careful tech selection to work out well.
5) Very much a preference. I prefer large propulsion plants and copious defensive firepower as my main line of defence. After offensive mission tonnage, space for armour and shields is very tight as a result. I usually ignore shields for a long time, and armour beyond 2-3 layers are mostly fit to maintain speed in nebula systems when applicable.
Your numbers look turtle-y to me, but not to the point of being unreasonable. However, I'd argue that a propulsion budget below 40% of mass makes it easier to mess things up ("10% more capability for only 3x the logistics overhead!").
6) See the above. What range do you need? If the last 20m make the difference between shooting first and hitting before they do, it's great. Otherwise, not. In the end, there are only 3 relevant ranges: enough to outrange enemy beams, enough to outrange enemy AMMs, enough to outrange enemy ASMs.
7) My preferred size is actually 7. Enough to fit a working sensors without eating too much into raw capability, and box launchers have 1 HtK as opposed to 0.
To some extent, the answer depends on details. Many missiles from one fire control? You may want relatively small missiles to make enemy PD less effective. One missile per FC to confound enemy PD? May as well make it moderately big (this is my standard approach for fighters, often ending with size 7-12). Point blank weapon of last resort that will strike within one 5 second interval and therefore bypass most PD? May as well make it huge, size 30 is not unreasonable.
Against some of the Usual Suspects, that will barely suffice. At reasonable tech levels I'm never truly happy with AMMs as a purely defensive weapon, once you include the logistics overhead. Beam PD, whether Gauss turrets, low-tech railguns or fast PD interceptors, offer more from my experience. However, AMMs may be an important offensive option especially in the face of a technlogically superior foe: You have the numbers to overwhelm point defence, and obviously a range advantage over the fanciest beams imaginable.
9) From a certain missile size (7-10 imo), it becomes a decent option if overkill is likely to be a problem. Keep in mind that enemy final fire PD will get a second shot against retargeting missiles.
10) Only one ship will use their engine, I believe the one with the more powerful one. Heavy use of tractor beams for military ships would offer many interesting options but is BLOODY annoying - the game will throw up whenever there's a single maintenance failure.