Hazed,
The lag you are trying to get a feel for is not really lag in so much as it is slack in the control cables (induced by constant forces being exerted).
To look at it simply, imagine a 190 or F4u with rod controls sitting on the ground. You move the stick left to right a few times, and the response will seem crisp and very responsive, because of the "direct" linkage with no stretch involved. Now imagine the same situation in say a T-6 or 109. The same response will be there, if the control cables are in tension. If there is slack, there will be a bit of lag, but that can be really a bad situation, if over tightened, thats bad too, but the lag will not exist and in some cases the force may be required more to move them if overtightened.
Anyways, now imagine the 190 or F4u, under speed. and you apply the aileron movement, the force required will be more so, as there is force reacting against your movements, but their is no lag what so ever, unless you count weak force application on the stick. Now hop back over to the 109 or T-6 and apply aileron movement as well. The force required and response should be the same if the cables are tensioned properly. Now if higher speeds are encountered, the possibility that the force required to move the control surface may be so great, that you can not exert enough to successfully move it, and yet may feel a little mnovement in the stick, this is due to the stretching of cables, as the bell cranks and pulleys attached to the stick act as a lever and allow you to apply so much force that you are actually slightly stretching the cable. That is the talk of lag I believe you are hearing... it is less prominent in fighters and much more so in the larger aircraft such as bombers... where the cables ran over much longer distances and where subject to more stresses due to their runs. This is mostly evident in the warbirds, even less so today. As for todays Warriors (civilian aircraft) and jets still using cables for controls, the systems benefit from design advances and the fact that they generally are under more checks and balances then the average warbird operator. That does not mean warbirds are less safe, it's just that most IA's and A+P's have no clue when it comes to the operation of a warbird system.
As for the oscillation of the nose in AH, that seems to be more pilot induced, and setting your stick forces to what you like and get used to can greatly reduce and / or eliminate the oscillations almost entirely.
As for the lack of adjustable inflight trim on the FW in the real world vs. the AH FW needing trimmming it seems to me that that is a case that this is a game, and as such, it can not be the same as the real world. WHile I feel it is the best attempt at a real world in WW2 it is a game none the less. This could change in AH2, and that is a question best asked to Dale, as he, and he alone can answer what will and is feasible to be programmed. In the end though, the minute amount of true data that exists has to be the problem in ever getting it 100% accurate. With the only possibility of doing so is getting an individual to allow you to up their real life FW and then, the PILOT coming back and programming it exactly the way it was experienced, and then that can not be accurate, because no real world operator is going to run 140 octane with methanol boost through his FW190 as the risks of damage to an irreplacable engine is too great.
Hope this is of some help, I in no way meant it to be rude, so no one need take it that way. There are plenty of others out there that probably can explain it better than I, and I am by no means the authority, just have been working on warbirds for the past 12 years.
Have a good weekend all.