It sounds to me like you have been a dedicated devotee of Lucifer the entire time, in your heart. 
You’re allowed. This doesn’t count as advertising, doing a review or discussing the person instead of the ideas and content.
Yes. You also probably had a bit of “con drop” from all the stress and excitement. That’s also normal. You got kind of high on adrenaline and endorphins and then you get withdrawal symptoms.
That’s also normal - sensing entities that are energy beings required the development of non-physical (psychic) senses, it’s not automatic for most people, and developing these skills is a lot like building muscle at the gym - you have to consistently practice the skills to get gradually better and better at them… this is why we have a bunch of free tutorials on working on them, and there are many videos and books out there that help.
I feel like the practitioner you contacted was successful and Lucifer is around you - this is my UPG, you should make your own mind up based on personal experience of course. One thing you can do now is ask him for a sign. Then be aware of your surroundings for synchronicities.
I don’t think so… You’ve been being invited to work with Lucifer for a very long time so I actually think the purchased working was redundant and he was already there for you. It was bound to be successful and only affirmed your dedication.
So this is the part that needs attention. I think you’re already past having a pact, and now comes the hard work. You don’t get handed anything on a plate, you have to do your part, continue asking for specific opportunities, and do your own work to be ready to recognise, accept and handle those opportunities when they come - that can be a lot harder than it sounds.
Using myself as an example, I have noticed I freeze and have let multiple opportunities for a specific opportunity pass by without even realising that’s what they were until it’s too late. So I am going to do another working to unfreeze myself, probably with Paimon who is good with psychology. The working continues to be successful but I’m the blocker - I’m doing it to myself and the rest is in place. I have to be more persuasive, and it’s more in my nature to let things go than try persuasion.
Well, let’s get into the specifics. What’s the first thing you want to improve and what workings do you have so far in play to get that?