Welcome to the forum! I am sorry you are suffering and suspecting lyme disease. To answer your questions: 1) You can get lyme more than once---it can become dormant for years and then reappear when there is a trauma to the body, And a person can be bitten by a vector and become reinfected. I do not think there is a permanent immunity to the disease, so you can get it again and again.
2) I'm not sure it is "easier" to get the second time around but I think that once a person's immune system is weakened by multiple infections, it may make them more susceptible to any kind of infection. Plus, if the person is not really cured, but only in "remission", then I think the disease can rear it's head very quickly when conditions are right. I think the best defense, in the long run, is to try and have a strong, healthy immune system that can fight the disease.
I hope you find the help you need and I hope you do not have lyme.
Best wishes to you, bablymers mom