We will soon be flying JFK-FRA on SQ25 and onwards to SIN on SQ325, all in J (same ticket). That gives us about 11 hours in FRA (10:40 am to 10 pm). We plan to go into Frankfurt to do some sightseeing, but first we'd like a shower. My questions:

1. Will we have any problems accessing the Air Canada or Senator lounges on arrival, given that our onward flight will be 11 hours later?
2. Will we have any problems accessing the Senator lounge in the evening before our departure if we use the lounge in the morning when we arrive? (Apparently the Air Canada lounge is closed in the evening).
3. Which lounge is more likely to have showers available after we arrive?