Hey there, gent. Really glad to see someone joining the HEMA fold. A few tips -
"Fighting with the German Longsword" By Christian Tobler was, until recently, incredibly expensive (think hundreds of dollars) and hard to find (the publishing company were real scumbags, got in a battle with the author, stopped printing and refused to give license to have it printed) I think the author eventually won publishing rights, so the situation may be improving, but its still somewhat hard to find.
Also, and believe me I say this with love (I started with Fighting With the German Longsword): the information is somewhat dated. Tobler's interpretation has changed considerably, but he hasn't published any new books.
If you really want to start off studying longsword (I might actually recommend starting with sword and buckler, but I wouldn't blame you if you told me to shove it) Here's what I recommend:https://learn-sword-fighting.com/
once you sign up and pay, you'll have access to a finite number of videos which you get to choose. I'd recommend splitting this with your friend and going for as many as possible.
Not only is the quality of the video instruction excellent, they have very active instructors who will critique videos of your sparring (also, bear in mind, most of the videos labeled "drills" are available for free here (https://www.youtube.com/user/LearnSwordFighting
Also, Armor. There are three things you really need. Most importantly Gloves, and I mean the big kind (lacrosse, ice hockey, etc) If you don't get them, you will give up the sport quickly. Why would I rate the gloves above the mask? because you can, if you wear eye protection and keep the fight controlled and slow, avoid the head. also, an accidental hit with the rawlings won't give you a concussion. However, it is entirely impossible to avoid strikes to the hand. and an accidental hit can easily break a finger. The gloves are vital.
However, if you ever want to truly train, you need a mask too. A regular fencing mask is fine. I have been training for a long time with rawlings and a foil fencing mask has never been insufficient.
finally, and least importantly, you can find something like this for a really good price (I got mine for 25 bucks free shipping)http://www.ebay.com/itm/Motorcycle-Full-Body-Armor-Spine-Back-Chest-Shoulder-Protector-Shirt-XL-XLARGE-/400701022447
Its for motorcycles, but it provides rigid protection where you need it.
seriously, those three pieces of equipment will last you from beginner to pro.