Bonus Gathering?

For higher ranks of bonus gathering, where you can get 3-4 bonus.

Do you always get the max availible, or do you have a chance to get 1/2/3 bonus materials.

The training tips seem to suggest the latter, but I'd like to be sure.

You will still get +1/2/3/4 of previous ranks.

the master title display as plant specimen gathering speed +5%, plant specimen bonus speed +3%. i dont know how its work or it just a mistake.

Most likely a mistake. It should probably be Specimen Bonus Gathering.