Storm,
Brew buckets are usually pre drilled with a gasket to hold an airlock, to use a lees stirrer you remove the lid completely.
Also a rule of thumb guide to sweetness can be found in my post
here.
For a 5 gallon batch a quick way to estimate is to use the same amount of honey (in pounds) as your yeasts alcohol tolerance. For example if your yeast's tolerance is 14%, then you'll want to use anything up to 14 lbs of honey for a dry mead, you'll need more than 14 lbs to to start leaving residual sugars. (Starting point: Any yeast tolerance % = base lbs in honey) For off dry you'll need to add 1 pound, for semi-sweet 2 pounds, for a sweet mead 3 to 4 pounds. This will get you very close to your desired result. If you are making a show mead, NO NUTRIENTS, it's best to estimate as [% - 1] = lbs of honey.
Yeast will often not hit their tolerance without nutrients.
To figure out what you need for larger batches, use the above formula to get your estimate for 5 gallons, then divide the amount of honey you need by 5 to get the amount of honey you need per gallon. Then multiply the amount of honey needed per gallon by the size of the batch you're making.
Always use the best tasting honey you can find, with a minimum of processing, filtering and heating.
Low alcohol meads are difficult, as active fermentations require lots of sulfite/sorbate to stop, they are best used when fermentations are slowing. Using less honey also means a less full bodied mead. A low alcohol Melomel with a predominately juice taste, as you're wanting, would likely spoil quickly without Lots of Preservatives AND Sterile Filtering.
Cheers,
Wrathwilde