often seen in the street without a hat

1. Have you ever stayed in a hostel? If so, where? Did you like it? If you haven't stayed in a hostel, would you?

Yes, stayed in many YHA youth hostels in women's dorms when I was younger. Some better than others in facilities or location but all excellent in price. I stopped because the people using them changed and I was no longer safe as a solo traveller. I was unlucky to be booked into a large dorm in the Lake District with the remainder of the dorm filled by one group of white middle-class women who decided to harass me. As it was my last night, and a Bank Holiday weekend so I knew there wouldn't be any alternative accommodation available nearby, I ignored them and went to bed early. I was subsequently "accidentally" kicked and trodden on several times. In the morning they got up early so I pretended I was asleep until they'd gone down to breakfast, then packed up to leave and have breakfast elsewhere. By the time I got downstairs they'd complained to the hostel warden and everyone else about me (don't know what lies they made-up) so everyone glared at me while the young warden, who was clearly relieved I was leaving and he wouldn't have to sort out a dispute, escorted me to the door. I'll emphasise that was my one and only negative experience in years of using many YHA hostels and was balanced out by many positive experiences, temporary friendships, safety in the companionship of other women travellers, and helpful wardens.

ETA: But if I'd grown up in a time and place where everybody had cameras in their pockets and immediate access to harassment via online posting then I probably wouldn't have risked hostel dorms, just for the record.
 
2. What is your favourite airport that you've been to? Why? 

Airports? No, thank you! Railway stations provide an endless variety of fabulousness though: architectural delights, public art, trains (most recently one with Paddington Bear on the side), and that atmosphere of humans in purposeful motion (outside depressing commuter hours, obv). Don't recall any notably good bus stations.
 
3. What is the best museum you have visited on vacation?

Recently? Plas Mawr. But I love almost all museums, especially the small quirky local ones about a single subject or obviously mostly run by one dedicated soul. The most unexpectedly good museum was the Cumberland Pencil Museum, now the Derwent Pencil Museum, that I was dragged to by friends. The best Big Day Out was the Black Country Living Museum. And my childhood fave was the Weald and Downland Open Air Museum, which in those days was basically a bunch of slightly random old farm buildings I enjoyed playing in with my family (also my introduction to the concept of the garderobe, lol).
 
4. Have you ever made friends while traveling whom you keep in touch with on a regular basis?

Pre-internet I met an Aussie woman in a Youth Hostel in England who was my holiday BFF for a couple of days and we kept in touch by letter when she went to live in Sweden. Then she came over to London for a few days so we went to the theatre together to see the Rocky Horror Show, lol. Then she joined a Christian commune and we lost touch.
And a couple of lesbians from Yorkshire invited me to stay with them after I rescued them from a spider in the YHA hostel in Boscastle.
But best of all are the BFFs for a day: people you meet and share perfect hours with then never see again. My first ever cup of Lapsang Souchong was a gift from an older solo traveller from New Zealand who had camped near my home village as a Girl Guide and was the only person I've met away from there who knew where it was. Or even random strangers who poke their noses into my life to share their local knowledge with a passing visitor, such as the White Van Man in central London who stopped and crossed three lanes of traffic to tell me the bus stop I was waiting at was in a temporary diversion and I needed to walk around the corner to a different stop.

5. Have you ever had a conversation with a seatmate on a plane?

No, but on trains and buses, yes. Especially, to repeat myself, kind people sharing their local knowledge with a passing visitor. Cardiff commuter woman saved me several minutes of potential frustration by explaining the layout of Cardiff Central Station and where the back exit is. And on a train I once reassured a man leading a group walk he had prepared using a map and google earth that there was indeed an extremely unlikely set of stairs where he needed them to be and his group wouldn't have to detour a long way around.
The most recent was on my way back from North Wales when a woman carrying a balloon animal sat next to me, and I eventually asked her if she'd twisted it herself as I'd only ever seen them made by street entertainers at the seaside, and she explained that her party were travelling home from the seaside where they'd acquired the pale pink quadruped of dubious species.

6. Et vous?