I also didn't get a chance to try Velib in Paris. When I came back into Paris a lot of time was spent with my AirBnB host (better referred to now as my long distance girlfriend). We used trains, RER and or metro to get around.
Apps:
I will say that the app "Next Stop Paris" was ideal. I could put my destination into the app and it would tell me which metro, which direction, which connection and supply real time walking maps as well as my position (a small blue dot on the map). I'd highly recommend this app if you have the device to take advantage of it.
I also used Google maps often when I had trouble searching for a place in Co-Pilot. I'd find a street adress there then plug it into Co-Pilot. I much prefer Co-Pilot for navigating it gives you speed limits and warnings when you're speed is over by 15 km (happened often coming into city limits with no speed sign). Co-Pilot maps are also similar to dedicated GPS devices so it's comfortable to use. Google maps for navigating was entertaining for how poorly it pronounces street names but the narration is really fast and somewhat hard to catch.
I didn't try uber at all in France, so can't report on whether it works. I used the trip advisor app sparingly but didn't rely on it very much.
I had plugged most of my information (reservation numbers, street addresses, open hours, etc.) into my android calendar. It was nice to have an easy day by day reference without digging through emails. By the time I had it all entered, I practically had my itinerary memorized - so rarely referred to it.
AirBnB was perfectly acceptable for me. The price to get a room in a home beat a hotel by quite a bit when a hostel wasn't available. I kept the app on my phone but never needed it because my stays all worked as planned. In many cases I had some trouble finding the homes because they don't always have the same street adress system we have. I was able to contact the owner and have them guide me, eventually I found them.
Finally I was completely happy with Mobile Passport. It's free and easy to set up. I was planning to fly to BWI but ended up flying to Boston. Fortunately Boston also has Mobile Passport capability. On the plane I took a selfie, scanned my passport (a little difficult while in the air), answered the four questions. I put my American SIM card back in my phone but left it in airplane mode until we were on the ground. When we landed, I submitted my form and received a QR code.
The hardest part was figuring out where to go. I asked and an airline employee pointed me to the Global Entry kiosks. Still not sure, I walked to the end and asked the CBP officer there, he pointed me to his window and walked to the other side - I got passed immigration faster than the people with Global Entry who were at kiosks behind me. After that I walked to baggage check and asked again. I was surprised that, again, they pointed me toward the trusted traveler side (Global Entry) and my daypack and I passed through in seconds. That doesn't mean I couldn't have been directed to secondary screening and had to take longer but the system worked great.
I did have a stop getting on the Spirit Flight, they wanted to see the gargoyle I bought for my son at Notre Dame because they weren't sure what to make of it. I had it rolled up with my dirty clothes so it wouldn't break.