Hello!
I was wondering about several aspects I encountered recently, can we discuss?

1. What a worker will do when nothing is planted on a plot, or crops reach 100/200%? Will he return to the town of origin, stay digging, etc?

I dont have any more lodging in nearby towns, so I have to hire workers from far away towns, it take nearly an hour for them to travel to the plot and start working.

2. Why exactly garden workers dont get any exp?

I have to spend CP to unlock Kamasylvia nodes (expensive!), then put Fadus to work there and level up, then try and fail to promote to Artisan, then minmax skills, and ONLY THEN assign this worker to a plot at Velia farm. It takes a huge lot of time, maybe several months, is it really worth it? How much more Artisan with minmaxed skills brings more profit than regular Professional? I'm not sure.

I already spent several thousands of Energy to hire ten Professional Fadus to attend my farms at Velia, and before that I invested several weeks leveling to Farming Master 1 to be able to plant Olde Moon Plots, its just cant be after all this I'm stuck at another time gate to be able to just grow food a little bit faster.

I haven't used workers on farms in years, it might be the same.  But the only time the XP gets calculated, the weeds and other items get brought back and basically anything is when the worker runs out of energy.  Also when crops get to 200% they don't know it, the only thing the worker knows is when the crops get damaged and need repair, that is when it takes the energy away.  This means that once everything is at 200% or empty the worker just chills doing nothing, while also not losing any stamina.

Whats your reasoning for sending workers all the way from Grana to Velia? Surely you arent capped on lodging in both Heidel and Calpheon where lodging is a lot cheaper and significantly closer to Velia than Grana is?

I dont personally use workers for my farms since I want the exp but I can say rather confidently that the difference in monetary gain between some average worker and a maxed out one is pennies at best.

Artisan Fadus has most stamina, 40, more than Artisam Giant (35). I'm not always at PC, so I prefer "giants" so they dont run out of stamina fast and stop working.
I dont need any more Farming exp since I'm at Master 2, there's no benefit for improving further I know about.

You see, the problem is that I need worker at my farms, otherwise crops get bugs or invasive plants almost every tick, not to say birds attack or lack of water, or something else. Farming is hard work, finding good spot is hard, garden requires permanent attention, but I'd like to do something else in the game while crops grow, and unattended they grow like one harvest per day, its not enough to consider OK time/effort investment against resulting product. 1 hour of grind is enough to just buy whatever is required for my Balenos meals from CM, provided somebody is willing to sell.

Or just abandon this activity altogether because it seems its extremely hard and time-consuming to get perfect or near-perfect setup. Six months to just grow crops, really?

Why workers get last levels exp so slowly? Last time I hired it was like 2 months ago, and they still 28.

Farming is mostly something you do if you like it or if it is needed to compliment another activity like cooking/alchemy. Its not rly a great money maker.

Crops gets hit by bugs/weeds way less if you grow them in a spot with optimal conditions and most ppl ive heard using workers for their farms have been ok with blue/yellow giants rather than spending a huge amount of time upgrading them to artisans. Actually lvling the workers used for farms has almost no effect other than their movement speed cutting the inital travel time since farm tasks arent based on any work speed value and their stamina max doesnt change based on their lvls.

Worker changes are comming soon though and that will bring an increase in their lvl cap and adjusting lvl 1-30 to be easier among other things but cant be sure until we get that patch.The optimal lvl at which you want to try promoting them will most likely change with this.

Worker exp is based on this formula: "Job time(Minutes)*1.2 + 10" and since farms have no workload and thus no job time being done it probably only recieves the base "+10" value per stamina spent. I know that short jobs, like making crates, with minimal travel distance is the fastest way to lvl workers but that also requires you to babysit them pretty hard since they run out of stamina very quickly.

All-in-all I think that you should consider a cheaper setup with 1-2 harvests per day depending on crop growth times and then use leftover CP for nodes for more passive silver income. Heidel has 15 lodging slots for only 8cp along with the benefit of being at a very central location in the world. Also, fertilizer cuts crop growth times by quite a bit and has to be done manually so the optimal result cannot be achieved with just workers.

I personally only hire green giants from very far away for my plots. It keeps them free of weeds well enough, you don't need anything more efficient. Having your farms in the ideal areas for your crops is a lot more important.

With the new auto feeding workers update on glabs, the need for giant workers for farms may be no longer present soon. 

That would be interesting indeed, if Goblin is auto-fed, then whats the point of having Giant or Fadus?

Indeed, that is the question