Not to be difficult but, you already know the answers.

How does one feel strongly about anything? Through knowledge and experience.

How does one have a personal relationship with anyone? In this case one must first except hat the person is a person. No person, no personal relationship. After that? Get to know them. Exchange value for value with them. You're in the hole there and always will be. We (who believe) owe Him everything but, attempts to pay will pay for nothing. We'll give because He first loved us. Add this to knowledge from the first answer and we'll find how he interacts with us in His Word. This will give us the experience.

If Jesus is the center of the question then God is not a vague concept. Those two are fairly well identified and described in The Word. If it's vague to you, read more of those words. That's where the knowledge that can lead to experience comes from, His Word. Commentaries and theologies can come later. Start with what all those commentaries are commenting on. Let them later help you after you have first thought for yourself.

And of course, no. You'll never get there. It's an endless journey. Once the relationship is established there is no end of the rabbit hole. Just how far down it you wish to dive. Every inch has it's trials, tribulations and rewards.