Hello! Sorry for such a late reply, this guide has been on the lowest of priorities for me because I've been hard at work on my Alistar guide lately.

I will be sure to update this guide as soon as time permits me, especially with the recent 4.13 patch nerfs and changes to other items, but to answer your questions:

1) Could you tell me in which order should I buy the items that you recommend?

As always, you will start out with Spellthief's Edge with wards and/or potions. Rush Sightstone and Sweeping Lens together, finish your Frost Queen's Claim, and somewhere along the line, finish your boots ( Sorcerer's Shoes, Mobility Boots, or whichever you please). At this point, you can build whatever your team needs. This guide is a bit outdated on items, so I will update it ASAP, but in general you will likely be buying a few on this list: Mikael's Blessing, Frozen Heart, Banshee's Veil, Locket of the Iron Solari, Ardent Censer, or many many many other possible items.

2) Do you have a youtube channel in which I can see some of your gameplay?

https://www.youtube.com/user/yummybluewaffleNA

3) Why you dont use ANY armor for you or your carry and ALL magic resistence?

That is a great question, and I literally JUST noticed I completely forgot to include some items like Frozen Heart and Randuin's Omen. I should have added these in earlier, not sure why I didn't, but this guide is of low priority right now. Once I finish the Alistar guide, I'll fix this thing up!

4) In your opinion which are the best ADC to support with this build?

Lulu is a very strong support champion for ADC's who like either poke or peel/protection in lane. However, she's not the best with aggressive, all-in ADC's because she is extremely squishy and lacks a lot of reliable, hard AOE CC. This makes her good with champions like Ezreal and Caitlyn (poke), as well as Vayne and Kog'Maw (protect). She doesn't synergize with champions like Draven or Graves that well since she can't lock the opposing bot lane down with lots of hard CC for these guys to deal their extreme early damage to get kills and snowball. She can protect these guys well and harass for them, but that's not exactly what these guys are looking for.

As for in relation to build, late game you are mostly focused on protecting and peeling, especially with the items you have. These means you can really help a Kog'Maw or Vayne stay alive as long as possible in a fight so they can deal their late-game hyper damage. These champions don't synergize well with champions like Leona who focus mostly on engaging. Lulu is the opposite in that she focuses mostly on protecting.

5) Is there any better skin to play with lulu?

Nope! All of her skins have no gameplay advantages, particularly since she is mostly a spellcaster. However, the skins do vary in the way Pix looks and the way the enemy looks and sounds when you use Whimsy to polymorph them. However, Glitterlance's particles all look the same regardless of the skin; the only real difference is their color.

Nice guide, thanks!

Greater Quintessence of Gold is really bad, you already have the gold income from the Spellthief's Edge and the utility tree mastery, you won't be needing it already.

Don't ever mention Clairvoyance and Clarity. Maybe you could use Clairvoyance for Nidalee but its a no on Lulu.

good guide man

Hybrid pen reds
Armor seals
Mr glyphs
Health quints

0/9/21 masteries

That should give you a good start.

Any suggestions?

Bad runes, masteries and build. -1

Really in-depth guide. I'll use it
+1