When did your interest in vintage textiles begin, and why - Have you ever used vintage fabric to create a garment or a corset? If so, was it any different from using modern fabric?
Generally vintage textiles are not suitable for corsetry unless they are very heavy and still strong. Many corsetieres and costume makers, make corsets and clothes from old curtains, drapes and textiles which they get from 'loft sales' in Statey homes and similar. This is a great source of vintage fabric for that sort of thing not only because it's 'period' but for corsetry because the fabrics are heavier and therefore more suitable. Personally, I have never ventured into vintage textiles for corsetry, but that is only because I haven't yet found something that inspires me to do so.
Do you think it's important to wear a corset underneath vintage garments to get the 'right' shape?
Yes, it is ESSENTIAL to wear good foundations underneath vintage clothes for a number of reasons. (I have taken 'vintage' to mean 40's / 50's syles as opposed to Victorian/Edwardian!).
The couturiers of yesteryear, (with the exception perhaps of Chanel who made it her goal to design clothes which did not need firm foundations) all used corsetry, whether in the form of a separate 'waspie' corset used by Dior for his 'new look' fashions, or in the form of the corsolette dress foundation used by others such as Givenchy whose muse was the beautiful Audrey Hepburn - as thin and waifish as she was, her gowns all contained corset foundations in order to get the desired sillouhete - the foundation was mostly there to support and enhance the lines of the dress.
In modern times, you only have to look at the recent royal wedding dress by Sarah Burton to know that corset technology in couture is still very much in use for when it comes to smoothing, shaping and perfecting the look of the vintage 'style' gown. A corset - however slim, trim and 'perfect' the figure of the person wearing is, is essential.
In other words, a corset foundation supports the garment it is designed to fit under, shapes the wearer, and by default ensures better posture which enables the dress to be worn to it's best advantage. This is true of most vintage fashions which aspire to that look. If you want to achieve the firm shape, cinched waist and smooth look which all work in combination to get the 'right shape', then a properly made and fitted corset, with steel bones, not plastic, is required.
Is there any sort of corset that is 'better' for beginners – underbust vs overbust, for example, or is it purely a matter of choice?
The best corset for beginners to make is an underbust. They are simple to construct, are good practice for a wide range of corsetry techniques, easy to fit, and comfortable to wear - a properly fitting underbust cincher will have a smooth transition between it and the flesh, there will be no bulges which are so common with modern elastic/lycra shapewear. Underbust cinchers also provide the best 'retro' sillouhete as they allow the wearer to use a bra for top support and this in combination with the cinched waist and consequently rounded hips, lends itself to the lovely hourglass shape which is so essential in 40's/50's fashions. A perfect example of this can be found in Sophia Loren's film "The Millionairess" from where the picture below is taken