What is the highest individual score from No. 10 in a Test?
And how many players have made an appearance in the IPL without ever having played a senior match?

Suyash Sharma was the 15th player to appear in the IPL not having played any senior cricket previously • BCCI
You're right that the 19-year-old legspinner Suyash Sharma had played no first-class, List A or other T20 cricket before he was selected for Knight Riders against Royal Challengers Bangalore in Kolkata last week.
You're right that the West Indian wicketkeeper Joshua Da Silva played against eight different countries in his first 19 Tests (he now has 22 caps, but still only eight opponents). Surprisingly, though, he's a fair way off this particular record: two players - the New Zealand wicketkeeper/batsmanBJ Watling and the Sri Lankan seamer Dhammika Prasad faced eight different opposition countries in their first 11 Tests. Another Sri Lankan, slow left-armer Lasith Embuldeniya, faced nine different countries in his first 17 Tests, and another left-arm spinner, Taijul Islam of Bangladesh, took on ten different opposition countries in his first 25 Test matches.
The game you're talking about, the opening match on March 31in Ahmedabad, featured the 41-year-old MS Dhoni keeping wicket for Chennai Super Kings, while Wriddhiman Saha, who's 38, took the gloves for Gujarat Titans. The combined total of over 80 years broke their own record, set in the second of the sides' meetings last season. Also last year, Dhoni's rival wicketkeeper in CSK's match against RCB was Dinesh Karthik, who was nearly 37 at the time (he turns 38 on June 1 this year).
Abul Hasan, who was picked for his seam bowling, marked his Test debut for Bangladesh in 2012-13 by thumping 113 from No. 10 against West Indies in Khulna. The only higher score from No. 10 came more than 128 years before that, in 1884, when England's Walter Read made 117 against Australia at The Oval.
The best bowling figures in the IPL season opener are 5 for 27, by the Royal Challengers Bangalore seamer Harshal Patel against Mumbai Indians in Chennai in April 2021. It kick-started a superb tournament for Harshal, in which he finished as the MVP, after taking 32 wickets, eight more than anyone else. The West Indian spinner Sunil Narine took 4 for 13 for Kolkata Knight Riders in the first match of 2013, and 4 for 20 in the opening game of the following season; in that same 2014 match, Sri Lanka seamer Lasith Malinga claimed 4 for 23 for Mumbai Indians.
Steven Lynch is the editor of the updated edition of Wisden on the Ashes