Sorry it took so long to get back to you :p
Basically you gain the covered in slime effect at the beginning of each combat assuming that you don't already have it. The number of turns you get depends on what your +ML is. 10 turns for +0ML. This will damage you for a larger amount the fewer turns you have remaining. Luckily, you can use chamois to wipe the slime off and start over. So when you find the slime doing too much damage... wipe it off
also there are various items that will give you slime resistance allowing you to sustain the effect longer.
As for the slime covered gear, you'll need to tickle the uvula and then equip the basic item. Eventually one of the slimes will eat your item and you'll receive the new one in return.
Here's a list of the basic item, their slime covered component, and it's end item after combining it with a nodule:
depending on whether you want the cudgel and shield or the scythe... the rusty components will run around 100k at current mall prices, but that's everything all at once. After that a nodule for each piece, and those go for about 200k each.
Head: Rusty diving helmet > slime covered helmet > corrosive cowl
Hand: Rusty grave robbing shovel > slime covered shovel > villainous scythe (2h)
Hand: rusty piece of rebar > slime covered club > pernicious cudgel
off-hand: rusty old lantern > slime covered lantern > grisly shield
Pants: rusty metal greaves > slime covered greaves > corroded breaches
Accessory: rusty compass > slime covered compass > malevolent medallion
Accessory: rusty chain necklace > slime covered necklace > baneful bandolier
bear in mind i wrote that back in May :p
If you have any further questions, ask :p I like to think that i have a pretty decent understanding of the tube