Are my fingertips suppose to get this tender? If so how long?

Yes. But not forever. The fingertip will develop a callus after a short while if you practice on a regular basis. It's simple, if you practice you get callus's. If you don't, you don't.

When can I play a song?

You can actually play some songs with as little as 2 chords. So as little time as it takes you to get a couple of basic chord forms together, a week maybe? There are many 3 chord songs as well. You don't have to know a bunch of chords to play simple songs. That's good news,right!

How often should I practice?

As often as you like! The quote I like to remember is "Fatigue is good, pain is not." Let your body (or fingertips) be your guide as to how much is to much. I will provide what are considered reasonable practice routines/goals for beginners in the course. Have patience with yourself and allow "muscle memory" to be created.

How long should I practice?

Beginners might feel limited as to how long they practice because there is not a lot of variety in what they are practicing. Just the same little things over and over. I recommend the beginner try a couple of short (10-15 minute?) sessions daily

Should I learn to play Acoustic or Electric guitar first?

I might recommend starting on Acoustic guitar, at least for a short while, and here's why. Less things to think about. Electric guitars have pick-ups, pick-up selectors, input jacks, you need an amplifier and a cable to plug in, volume controls, tone controls, whammy bars (ugh!). Lot's of things to "get in the way" of just learning guitar basics.

Standing up or sitting down?

Sitting at first makes more sense to me. Standing involves getting a strap, adjusting the strap to your liking. Not to mention to most it feels downright awkward at first. Like starting on acoustic, starting out sitting down presents fewer obstacles.