Hello, everybody. I just signed up for Guitar tricks 2-3 weeks ago and I have been playing the guitar for the last 3 or 4 weeks. At the Guitar fundamentals course 1 I learned a lot of things and I am still improving. I can play all the chords cleanly and I am currently trying to change between them. Everything is going fine but my biggest problem is holding the guitar and the position of my fingers. I have some general and some personal questions about holding the guitar. The more general ones are;

1) Should the guitar be aligned paralel to our body?

2) When holding the guitar should the neck of the guitar be paralel to the floor or can it be a little bit higher(pointing upwards).

I have 1 electric guitar and 1 acoustic. I can hold the electric very comfortably ıt just sits on my lap and ı place my forearm on it like this: https://ibb.co/b7cZdk

I hold my acoustic like this(I place my forearm on the upper back of the guitar and my bicep doesn't touch it): https://ibb.co/gJtUB5 when I do this ı can control my fretting hand very easily but the guitar slides against my body. When I place my bicep on the upper back of the guitar like this: https://ibb.co/njWhW5 It doesn't slide away and I can play but I can't control my fretting as well as the first holding style and also the pick sits at the end of the soundhole the pick is very close to the neck of the guitar. When I put my right arm backwards for placing my picking hand at the start of the sound hole my left arm moves too and I feel so much strain in my left arm and fretting becomes so hard. What should i do to find the best holding style for me? I am considering buying a strap, is it necessary and what is the best holding style while wearing a strap should I hold the guitar as displayed in the first or second picture?

My second problem is about the positions of my fingers. When I do some finger exercises like spider legs exercise my index and my pinky don't stay as flat as my ring and middle finger. It looks like this: https://ibb.co/h0sWr5 When I play the chords my fingers stay pretty flat but at the C chord my index finger bends a little bit like this: https://ibb.co/iAdhyk

Also there is a video of me playing the spider legs exercise Am I doing it right? Are my picking and fretting technique appropriate?

https://www.youtube.com/watch?v=MgOfsaBSxaU

Thanks for reading. I appreciate all of your comments