The third was about the difficulties of making a successful return from injury, the way Nadal has, reaching the final at all eight tournaments he's played in 2013 after going more than half a year between matches.
Federer shrugged and replied simply: "I don't know. I have never been out for seven months."
No he hasn't. Federer is always around, particularly at Grand Slam time. When the French Open starts Sunday, he will be participating in his 54th consecutive major tournament, a run that began with the Australian Open in January 2000. That's the longest such streak among active players; no one else comes within two years of Federer.
"For me, it's just something I just kept on doing. Now here we are," said Federer, who is seeded No. 2 in Paris and was drawn Friday to face qualifiers in each of the first two rounds.
"It's incredible. I never thought I was going to play that many, have that many opportunities to do well at the Slams. And clearly I'm happy about it, but they don't buy me victories, you know," added Federer, whose record 17 major titles include the 2009 French Open. "But it shows maybe great stamina and (an) injury-free career, in a way."
Nadal, who's dealt with recurring knee problems, will be back in Grand Slam action after nearly a year's absence from the four most important tournaments in tennis. At least he's in the field at Roland Garros, something Andy Murray and Juan Martin del Potro can't say: Both of those past U.S. Open champions and current top-10 players withdrew because of health issues.
Seven-time French Open champion Nadal dismissed the notion that he might be excited about getting back on the Slam stage for the first time since a second-round loss at Wimbledon last June.
Each tournament is as important as any other, the 11-time major title winner insisted Friday, going so far as to say: "If you can ask me if I win one Grand Slam during the whole year or win six tournaments, like I already did, I will choose (winning) six tournaments."
He explained: "When you win (a) Grand Slam, you are happy one week or two weeks. When you are winning (other) tournaments, you are having the chance to be happy and you feel that you are doing the right things during the rest of the time."
By that standard, Federer has not had an especially happy 2013.
His record is only 18-6, and he enters the French Open without a title for the season for the first time since 2000, his second full year on tour. Federer's played in only one final, a straight-set loss to Nadal in Rome last weekend.
Despite that, Federer declared: "I'm at the level I want to have for this tournament."
Now 31, and a father of twin girls, Federer tweaked his schedule this year to give himself a bit of a break. He skipped the hard-court event at Key Biscayne, Fla., and went nearly two months — from March 14 to May 7 — between matches.
"For me, it's important to stay injury-free, to give myself time," Federer said, "so when I come back, I'm fresh and motivated."
He's not merely about longevity or consistency, of course, but also excellence.
Federer doesn't just show up at Grand Slam tournaments: He has reached at least the quarterfinals at the last 35 of them, and earlier put together runs of 23 consecutive semifinals, and 10 consecutive finals.
If he plays at Wimbledon, where he is the defending champion, and then the U.S. Open this season, Federer will tie the record of 56 Grand Slam tournaments in a row, set by South Africa's Wayne Ferreira from 1991-2004. Not necessarily the stuff of great acclaim: Federer didn't know what the existing mark is.
The second-longest current set of Grand Slam entries belongs to Spain's Feliciano Lopez, with 45. Top-ranked Novak Djokovic has never missed a major tournament since entering his first in 2005, making the French Open his 34th in a row, but he has stopped playing in the middle of Grand Slam matches.
Federer is fond of pointing out, as he did again Friday, that he never has retired during a match in progress, and only twice has pulled out of tournaments after having competed in the draw.
He also noted that he's never really come close to missing a Grand Slam tournament during his streak.
"In a Slam, where you know you're going to enter best-of-five-set matches over two, three weeks, you have to be at your best and you need to feel like you can compete with the best at the highest of levels for a long period of time," Federer said. "There's no shortcuts in best-of-five-set matches, and that's where I think I was always up for the challenge. I'm very happy that I was able to do that for so long so far."