1. this is because in my woocommerce I have configured two decimals in the price and in the function woo_product_price_2sats I format the price in $product_p_formated with rtrim($total, ".0"); to avoid having zeros that I don't need. You can solve it in a very simple way, either adding two decimals in the woocommerce price settings (woocommerce>settings) or commenting that line of code and in the fiat price print print "<span class='fiat-price'>&nbsp;{$product_p_formated} €</span>"; replace $product_p_formated with $total.

function woo_product_price_2sats() {
	global $woo_currency;
	$all_meta_data = get_post_meta(get_the_ID());
	$total=$all_meta_data['_regular_price'][0];
	$price_oracle_url = "https://blockchain.info/tobtc?currency=$woo_currency&value=$total";
	$ch = curl_init($price_oracle_url);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    $data = number_format(ltrim(curl_exec($ch), "0."));
	$product_p_formated=rtrim($total, ".0");
	curl_close($ch);
    print "<span class='btc-price'>{$data} Sats&nbsp;</span>";
	print "<span class='fiat-price'>&nbsp;{$product_p_formated} €</span>";
} 

2. Yes, I've had those problems too (that's why they appear disabled), it's because woocommerce doesn't have a filter to differentiate between the cart page and the minicart and that breaks it, however I already have a way to do it by digging in the woocommerce template files, I haven't had time to develop it yet, but it's the starting point.