Find (and buy) the book "Complete guide to Anchoring and Line Handling" by David G. Brown. It is published by Hearst Marine Books.
It is not a huge book, but it covers every question you have regarding anchoring.
What type of anchors work best in what bottom
What size of each anchor is recommended for a given boat size, and why
What type of rode is appropriate: what size, length, and type
Regardless, here are some quick suggestions:
*For your 26' boat, I'd recommend 5/16th BBB chain. You'll likely tear out deck hardware before the chain breaks. The rule is: 1 foot of chain (.3 meters) per foot of boat- MINIMUM, and more is better!
*Anchors have a similar rule: 1LB of anchor per foot of boat- MINIMUM, and more is better!
*Put a swivel between the anchor and the chain, or between the chain and the rope.
*If using an all-chain rode, you'll want to rig a rope "snubber".
Regarding the "recommended anchor sizes" you'll see from manufacturers- those are rated for 20 knots of wind. If you need the anchor to hold in more than 20 knots, you'll need to go bigger than they recommend. A 30-35LB CQR would be a great choice, but carry more than one anchor (and more than one type). The Fortress FX-16 would be another excellent choice, and these don't rely on weight to work (the general rule of 1LB per foot does not apply here).
An anchor roller on the bow will make storing and deploying the CQR easy, while a storage bracket is recommended to hold the Fortress, which is light enough to be easily handled.