GuzziMoto

Somewhere in this forum I wrote something up about how the early forks have basically zero compression dampening. I also talked about how, if you block off one of the two large bleed bypass ports in the cartridge tube, you can force the oil to go through the piston and valve stack and end up not only with dampening but have an adjuster that does something beyond the last inch of travel.
The early forks have two large bypass ports that allow so much oil through them that the oil only needs to go through the piston and valving after the piston is past at least one of the two ports. And that doesn't happen until you are something like 3/4 the way through the suspension travel.
Changing the oil won't help much unless you resolve that issue in my opinion.
New springs are good, but we found that once we actually got the forks to have compression dampening we were OK with stock springs. At your weight, you may want stiffer springs, but I would address the utter lack of compression dampening first.
From memory, I was working on the forks and happened to put the forks together without the springs installed. That made it easy to see what is going on. No matter what I did with the compression adjuster the compression leg had zero resistance to being compressed. I looked at it closer and saw the two large bypass ports and figured out that I could block one of them off and that would force at least SOME of the fork oil to go through the valving in the piston. The way it was stock it only really forced the fork oil through the valving after the piston was past at least one of the two bypass holes. So really, it was more like an adjustable hydraulic bumpstop.

In the end widgets like those are always a compromise. The problem is that they can only adjust the whole map in one direction or the other. Typically parts of the stock map are too lean while other parts are too rich. There is no one adjustment widget that will fix the whole map. Depending one where you ride, how you ride, and what bothers you, you may find that overall one of those widgets makes you think things are much better. It also might make you think things are much worse. the reality is likely somewhere in the middle. but due to the way they work they are at best a band-aid. Either the GuzziDiag software (too much trouble for me) or an adjustable modifier like a PowerCommander can actually allow you to take away fuel where you have too much and add it where you have to little.
I look at widgets like the one in question as a overly simple answer to an overly complex question.

In order for the transmission to shift one end typically has to be spinning. Either the motor running to spin the input shaft or the rear wheel spun to spin the output shaft.
Not saying you don't have a trans issue, but in order for the trans to shift smoothly the gears must have at least a little movement to them. Otherwise the dogs can't go into their slots and the gear teeth won't mesh.

The first part of suspension adjustment is setting sag. That is done by turning the preload collar on the shock at the rear. I believe the Ohlins had a remote adjuster for that. Unless you have non-stock front forks adjusting preload at the front is something that requires taking the forks apart. 
Setting sag has been covered here and else where at great length. Mainly it is measuring how much the bike compresses the suspension from full extension both under its own weight and under the weight of the bike with rider(s and luggage). Typically you want around 10-15% of the suspension travel to compress under just the weight of the bike and 25-35% with the bike, rider(s), and gear.
When you add more spring preload typically you also want to add a little more rebound dampening. You may also want more compression dampening but that depends. You have to remember that adding preload does not make the spring stiffer(unless you have replaced it with a progressive spring) so if you need to add preload because the bike is carrying more weight then you also likely want to add compression dampening to help control that extra weight.
 
My suggestion, add enough rear preload so that the bike sit roughly the same level with the extra weight as it did without the extra weight. A good trick to do this is at night using the headlight to show you the attitude of the bike. Have the headlight shining against something like a wall or garage door. You want to be around 6'-10' away. Take note of where it is hitting, how high it is shining. Then add the extra weight. Then add preload so the headlight is shining at roughly the same height as before. Now add a couple clicks of compression and rebound (clockwise on the adjusters). Then ride. If the bike seems to wallow or feel pogo'y (bouncing up and down) add more clicks a couple at a time until it feels controlled.