How many boveda packs can I use ?

I would probably go with two or three Boveda packs for your 50 count humidor.  Even though you'll only have it half full, you'll need to maintain that size humidor and I've read that humidors that aren't full can be harder to maintain humidity for.  Adding more Bovedas than you need isn't a problem, it'll just make them last longer between replacements / recharges.

as Charlie said, 84% is too high, big risk for moldy cigars, many like 65 or 69% so the cigars are easier to light, smoke, and keep lit right out of the humidor but if you prefer a more moist cigar go for the 72 or 75% packs.

@the3stogies, More is better IMO simply because they will last longer between recharges.

@Sevenhilli, yes two is pretty much the minimum, there are a few of us who use extras and/or a gel or silica humidifier.

I have a buddy that likes his smokes at 78 + rh (he also smokes a LFD Airbender 6x60 in less than an hour) He buys a box and smokes it, anything that he wants to keep for more than a couple of weeks goes into a different box at 69Rh.

If it works for you it's good, just keep in mind that anything over 70RH means its a lot more likely to sprout mold.    

If you looked @ the Bovedo website it tells you 14 days is required to season a humi using there 84% packs. 1 pack for every 25 cigars the humi holds. So set it and forget it for 14 days. Don't open it just leave it alone. I would worry more about that glass top leaking though. Not reliable and may require additional maintenance for a tight seal.

Far from an expert but I use to smoke my gars on the higher RH side. I have lowered to 65% and all I can say is that I never have burn issues, no more cracking  and the cigars smoke really well. There is a huge difference for me at least. 

Easy way to find out what is best is to get some tupperware and add the same cigar to each one and using all the different RH packets. You can get the mini's. Then start smoking them and write down what you experienced. Let the cigar tell you what it wants to smoke at. Not a difficult process, Cigars need care and attention like plants, wine etc. This is not a "I am too lazy hobby". It can become an expensive lesson if you are not willing to put the time and effort into it. Once you get your humi and cigars right it becomes even more enjoyable. 

Many have said be prepared for mold when using RH in the high 70's. If it is something your smoking all at once then it should not be a huge factor. If you are storing them for a long period of time at that high of an RH u may as well flush your $$ down the ****.

Or take them to your local B&M and have tell you you have tons of plume on a moldy cigar. 

I suggest searching the forum and reading others experiences and suggestions. Lots of info here for should.

I don't think I've ever read any recommendation to store cigars at 84% rh.  This could be an expensive lesson once mold sets in.

^^ That will cause mold too....

Looks good.

You already have your bovedas bought, and they are rechargeable so why switch?

Toss them in distilled (holy) water for a day or two.