What an intriguing question. I’m having some pioneer-prairie-blacksmith-shop fantasy thoughts on how you might be able to toast the inside of your barrel on your own. Depends on how crazy you want to get. Before I go there — with all the non-OSHA approved tactics — let me address your other mini-questions.
“Untoasted barrel — how will this work for red wine?” I often use about 1⁄3 untoasted wood in my wine aging. It contributes mouthfeel and finish (not to mention barrel-aging dynamics like micro-oxygenation) without contributing toast or char. It’s a net positive. However, you won’t get the typical “toasty” elements one might expect from oak-barrel aging.
“Will I need to add toasted oak to my oak barrel?” You could but you don’t have to. Use toasted oak chips in a nylon stocking a la easy tea bag style. You’d be surprised by all the high-quality oak chips, beans, segments, and pieces available today.
“I’ve only used Winexpert — is this the best brand out there?” Winexpert is one of the two major manufacturers of wine kits, RJS Craft Winemaking being the other. Both have a full spectrum of kits, ranging from the affordable value brand kits, to the much pricier high-end kits. Not knowing what line of kits you purchased from Winexpert one generality is that the value brand kits have more concentrated grape juice, meaning more water is added to reach proper volume, while the higher-end kits have less concentrated juice so less water is added, while the top-end kits generally are 100% grape juice. The higher end kits often have grape skins included in their red wines to get some tannin/polyphenol extraction during fermentation as well. I know in WineMaker we frequently write about kits and each year we run our annual WineMaker International Amateur Wine Competition where wine kits are judged up against fresh grape wines. So you can flip though some issues, or the website, for topic specific article and check through the results of the various winner’s circles from the Competition to see what kits are winning awards. Each December-January issue of WineMaker, we publish a Top 100 Kits based on results from that year’s Competition as well. Finally, you may want to check out my response to Ted earlier from this same column for possible help with acid balance, as that can be one of the keys to crafting a balanced wine (kit or otherwise).
Now, on to how to toast your own barrel, if you’d like to. In an abundance of caution I’ll say “don’t try this at home” and indeed, I never have, but I imagine that if you heated up some small metal bits, say like some screws and nuts, and somehow rolled them inside your barrel, you’d heat and toast the inside. Your barrel is already fully formed so you can’t upend the barrel head over an open flame like the coopers do, but how about heating up (in a fire or a very hot oven) a length of chain, then with tongs and gloves feeding that through the bunghole and rolling it around on the inside of the barrel? Quench with water if it gets too hot, and watch for burning/charring aromas. I’d go for a nice toast as opposed to a big burn. I’ve never done this before myself but if I were in your situation it’s what I’d try . . . very carefully.