Hi,
1.
The with of the frame depends on the number of columns you configured in your menu item settings.
The height of the frame depends on the height of the content inside.
If you wish to increase the height of the frame you can use CSS.
For example:
.hikashop_container {
min-height: 380px;
}
2. The - / + / quantity input layout is also being affected by your template's CSS.
Such CSS would help:
.hikashop_product_quantity_main table {
display: inline !important;
}
However, you might prefer changing the "Quantity input method" setting in the HikaShop configuration in order to change the look of the quantity input area. The table layout you have right now is an old one.