1.Should i put coupling discs under Michell cone shaped feet
I wouldn't unless you're trying to protect the surface of the shelf at all costs. These discs are furniture/floor protectors, nothing more.
2.Should i try any mats?
Definitely not. The platter/clamp system is designed specifically to couple the LP to the platter.
3.Will upgrading to Orbe 6cm acrylic platter reduce the brightness that i currently have?
Possibly, but I don't think this is a very cost effective upgrade, especially since you end up with an expensive spare Gyro platter collecting dust. I tried it and found that the Orbe clamp was responsible for at least half of the Orbe platter's sonic improvements.
The Orbe clamping system is pricey at around $350, but I consider it money well spent. It darkens the sonic background and lowers surface noise quite a bit. It's also much easier to use and couples the outer edge of the LP to the platter more firmly than the Gyro's press-on clamp. Use just enough clamping pressure to couple the LP to the platter and no more. Over-tightening the clamp sounds slightly bright/edgy.
If you're experiencing a problem with brightness, I'd look at your cartridge loading and/or VTA/VTF, or possibly address the problem downstream. In some systems the Gyro can sound a little analytical, but for the most part it's a well-balanced TT top to bottom with plenty of weight and body.
4.Should i risk enlarging the armboard for this new Vee-Tuff ($149=99) gadget that allows VTA adjustments while playing music?
I've heard the VTAF and don't care for it. It decouples the arm from the armboard which I find has a deadening effect on the note attack. VTA on-the-fly is a needless distraction, IMO, especially if the VTA device has a deleterious effect on the sound. If you're dicking around with the arm settings with every LP you spin, you're focusing-in on the sound rather than the music. Just set VTA for the best sonic compromise and forget about it.
5.Is it worth shelling out for a Pedersen mod and where can i get it from?
I don't think so. The Pedersen mods rely on mass-loading the chassis, which I think compromises the Gyro's rhythmic drive. I've tried the Denso-damp tweak---a less severe form of damping via mass-loading---and it definitely dulled the Gyro's pacing. I ended up substituting it with a very small amount of tak putty to lightly damp the aluminum chassis, but you have to be careful; too much damping will make the 'table err toward sounding musically lifeless, even if it adds a little more sonic detail.
6.Is it better to level the platter with rotating spring adjustment or by rotating conical feet?
Thread the feet all the way in, but don't over-tighten them. Just make them gently finger-tight. Likewise the arm and armboard mounting bolts. Over-tightening the hardware stresses the materials and raises their resonant frequency, which can sound thin and bright. Level the chassis/platter using the spring adjusters, but only after assuring that the support shelf is dead-nut.
Hope this helps, and good luck.