Just starting out

Well we are in the early stages of starting out, our orientation isnt til dec 4th but til then ive been doign alot of reading and some website are excellent help. we live in macomb county and i dont know about you but i just dont know who to trust to go with. we are starting with catholic services as we know people from the past dealing with them. but as i read some posts i get more confused. i hear people mention about failed adoptions and having the child taken away after sev monthes, cs told me the mom and dad have 21 days from court date to change their mind mandated by mi law. how were thes bithparents able to come back after so long and take your babies??? also i know from past brds people dont like when i say this but cs of macomb doesnt allow birth mom to have hx of drug use, hiv, or certain stds, which i like b/c personally i dont wanna a baby whose having withdrawls from drugs or medical probelms stemming from this, or passed on hiv thru blood. i still havent decided on open, closed, or semi open, im so confused. i do know that selfish as it may come across but i dont want the bmom to have any visitations, or meetings. i am open to pics and letters thru the years but i dont want her to know the child personally or knwo my personal info, so is this considered semi open. i know the agency i have a meeting with says they mostly do open adoptions,how do all you feel about this. i need to be prepared for everything the ups the downs, the questiosn to ask, and basically what were gonna go thru to get a baby. any help woudl be great, but please dont judge my decisions. also once a birth mom chooses you, how much notice are u typically given form when she chooses you til she delivers-monthes, weeks, days??? just not quite sure when the time comes how to prepare my work for a possibility of last minute notice a baby may be ready. and last questions are u guys decorating nursery before delivery, and what about a baby shower.